feat(android): the tap highlight goes, a press state replaces it

The phone drew a grey box over the bounding rect of whatever was
tapped, which is the web view saying what it is. It is gone in one
declaration: `-webkit-tap-highlight-color` is inherited and an
inherited property crosses a shadow boundary, so `html` in index.css
reaches every shadow root in the app. Measured three roots deep,
rgba(0, 0, 0, 0.18) before and rgba(0, 0, 0, 0) after.

Removing it removes the only touch feedback several surfaces had, so
the press state is part of the same change rather than a later polish
item — with the highlight gone a held row measured the *hover* tint,
which on a phone is synthesised by the hold itself and outlives it.
The four lists' rows, the tab bar, the sidebar's destinations and the
shared context-menu item take --yj-press-overlay on :active; the cards
already had scale(0.97). The press selector carries a state class
because a row is .track-row.selected.active, so a bare :active shows
nothing on the row a phone is most likely to press. And those
surfaces' hover tints move behind (hover: hover) and (pointer: fine),
which is #68's gate applied to a tint rather than a revealed control.

user-select, the other half of the Findings, was already done: the
first rule in index.css covers the shadow roots for the same reason.
touch-action: manipulation is declined — the 300ms delay it is offered
for is already absent on a width=device-width viewport, and what it
would really change is the gesture stack tuned by measurement on a
device this session cannot measure.

Closes #54

frontend/src/components/bottom-nav/bottom-nav.ts

@@ -89,6 +89,17 @@ export class BottomNav extends LitElement {
             color: var(--yj-accent, #ffd43b);
         }
 
+        /* The press state (#54). This bar is the phone's primary
+           navigation and had no feedback of its own at all -- what a
+           tap produced was the web view's tap highlight, a grey box
+           over the whole 48px cell, which index.css has now taken
+           away. The .active rule above is which tab you are *on*; this
+           is the tab being pressed, so they are a colour and a
+           background rather than two colours. */
+        button:active {
+            background-color: var(--yj-press-overlay, rgba(255, 255, 255, 0.12));
+        }
+
         button:focus-visible {
             outline: 2px solid var(--yj-accent, #ffd43b);
             outline-offset: -2px;

frontend/src/components/playlist-details/playlist-details.ts

@@ -1357,8 +1357,14 @@ export class PlaylistDetails
             user-select: none;
         }
 
-        .track-item:hover {
-            background-color: var(--yj-hover-overlay, rgba(255, 255, 255, 0.05));
+        /* A hover tint is for a device that hovers (#54). A hold
+           synthesises a hover in the WebView, so ungated this arrives
+           because a finger touched the row and stays after it has
+           gone; the press state below is what a tap gets instead. */
+        @media (hover: hover) and (pointer: fine) {
+            .track-item:hover {
+                background-color: var(--yj-hover-overlay, rgba(255, 255, 255, 0.05));
+            }
         }
 
         .track-item.selected {
@@ -1378,11 +1384,13 @@ export class PlaylistDetails
             cursor: pointer;
         }
 
-        .track-item.phantom:hover {
-            background-color: var(
-                --yj-hover-overlay,
-                rgba(255, 255, 255, 0.05)
-            );
+        @media (hover: hover) and (pointer: fine) {
+            .track-item.phantom:hover {
+                background-color: var(
+                    --yj-hover-overlay,
+                    rgba(255, 255, 255, 0.05)
+                );
+            }
         }
 
         .track-item.phantom.selected {
@@ -1392,6 +1400,19 @@ export class PlaylistDetails
             );
         }
 
+        /* The press state (#54): the feedback a tap has now that the
+           web view's own highlight box is gone (index.css). Last, and
+           carrying a class, because a selected or playing row is two
+           classes deep and a bare :active would lose to it. */
+        .track-item.selected:active,
+        .track-item.active:active,
+        .track-item:active {
+            background-color: var(
+                --yj-press-overlay,
+                rgba(255, 255, 255, 0.12)
+            );
+        }
+
         .phantom-row {
             grid-column: 1 / -1;
             display: flex;

frontend/src/components/queue-panel/queue-panel.ts

@@ -581,8 +581,14 @@ export class QueuePanel
             contain: strict;
         }
 
-        .track-item:hover {
-            background-color: var(--yj-hover-overlay, rgba(255, 255, 255, 0.05));
+        /* A hover tint is for a device that hovers (#54). A hold
+           synthesises a hover in the WebView, so ungated this arrives
+           because a finger touched the row and stays after it has
+           gone; the press state below is what a tap gets instead. */
+        @media (hover: hover) and (pointer: fine) {
+            .track-item:hover {
+                background-color: var(--yj-hover-overlay, rgba(255, 255, 255, 0.05));
+            }
         }
 
         .track-item.selected {
@@ -597,6 +603,19 @@ export class QueuePanel
             background-color: var(--yj-selection-bg, rgba(100, 160, 255, 0.15));
         }
 
+        /* The press state (#54): the feedback a tap has now that the
+           web view's own highlight box is gone (index.css). Last, and
+           carrying a class, because a selected or playing row is two
+           classes deep and a bare :active would lose to it. */
+        .track-item.selected:active,
+        .track-item.active:active,
+        .track-item:active {
+            background-color: var(
+                --yj-press-overlay,
+                rgba(255, 255, 255, 0.12)
+            );
+        }
+
         .track-position {
             font-size: var(--yj-text-sm);
             color: var(--yj-text-tertiary, #888);

frontend/src/components/sidebar/app-sidebar.ts

@@ -95,8 +95,15 @@ export class AppSidebar extends LitElement {
             text-align: center;
         }
 
-        li button:hover {
-            background-color: var(--yj-bg-elevated, #343a40);
+        /* A hover tint is for a device that hovers (#54), and this
+           component is on a phone too: below 600px it is what
+           bottom-nav's "More" sheet mounts, where a hold
+           synthesises a hover and leaves a destination looking picked
+           after the finger has gone. */
+        @media (hover: hover) and (pointer: fine) {
+            li button:hover {
+                background-color: var(--yj-bg-elevated, #343a40);
+            }
         }
 
         li button:focus-visible {
@@ -108,6 +115,14 @@ export class AppSidebar extends LitElement {
             background-color: var(--yj-bg-overlay, #495057);
         }
 
+        /* The press state (#54), after the .active rule and at the same
+           specificity, so pressing the destination you are already on
+           still says something. It is what a tap gets now that
+           index.css has taken the web view's own highlight box away. */
+        li button:active {
+            background-color: var(--yj-press-overlay, rgba(255, 255, 255, 0.12));
+        }
+
         li button p {
             margin: 0;
             white-space: nowrap;

frontend/src/components/smart-playlist-details/smart-playlist-details.ts

@@ -516,8 +516,14 @@ export class SmartPlaylistDetails
             user-select: none;
         }
 
-        .track-item:hover {
-            background-color: var(--yj-hover-overlay, rgba(255, 255, 255, 0.05));
+        /* A hover tint is for a device that hovers (#54). A hold
+           synthesises a hover in the WebView, so ungated this arrives
+           because a finger touched the row and stays after it has
+           gone; the press state below is what a tap gets instead. */
+        @media (hover: hover) and (pointer: fine) {
+            .track-item:hover {
+                background-color: var(--yj-hover-overlay, rgba(255, 255, 255, 0.05));
+            }
         }
 
         .track-item.selected {
@@ -533,6 +539,19 @@ export class SmartPlaylistDetails
             background-color: var(--yj-selection-bg, rgba(100, 160, 255, 0.15));
         }
 
+        /* The press state (#54): the feedback a tap has now that the
+           web view's own highlight box is gone (index.css). Last, and
+           carrying a class, because a selected or playing row is two
+           classes deep and a bare :active would lose to it. */
+        .track-item.selected:active,
+        .track-item.active:active,
+        .track-item:active {
+            background-color: var(
+                --yj-press-overlay,
+                rgba(255, 255, 255, 0.12)
+            );
+        }
+
         /* Phantom rows span the full grid */
         .track-item.phantom {
             display: grid;

frontend/src/components/track-list/track-list.ts

@@ -1201,8 +1201,16 @@ export class TrackList
       padding-left: 6px;
     }
 
-    .track-row:hover {
-      background-color: var(--yj-hover-overlay, rgba(255, 255, 255, 0.05));
+    /* A hover tint is for a device that hovers (#54): a hold
+       synthesises a hover in the WebView, so ungated this is a
+       highlight that arrives because a finger touched the row and
+       then stays there after it has gone -- which reads as a
+       selection the user did not make. Same gate, and the same
+       mechanism, as #68's revealed controls. */
+    @media (hover: hover) and (pointer: fine) {
+      .track-row:hover {
+        background-color: var(--yj-hover-overlay, rgba(255, 255, 255, 0.05));
+      }
     }
 
     .track-row.selected {
@@ -1239,6 +1247,23 @@ export class TrackList
       background-color: var(--yj-selection-bg, rgba(100, 160, 255, 0.15));
     }
 
+    /* The press state (#54), and the only feedback a tap has now that
+       the web view's tap highlight is gone (index.css).
+
+       **Last, and as specific as the state rules above**: a row that
+       is selected and playing is .track-row.selected.active, so a
+       bare .track-row:active is one class short of it and a press
+       on the row a phone is most likely to press -- the one it just
+       selected -- would show nothing. Instant rather than
+       transitioned, because the only measured statement here about
+       transitions on a list is that two card grids removed theirs
+       for software-rendering repaint cost. */
+    .track-row.selected:active,
+    .track-row.active:active,
+    .track-row:active {
+      background-color: var(--yj-press-overlay, rgba(255, 255, 255, 0.12));
+    }
+
 
     .cell {
       overflow: hidden;