feat(android): a name is not a link on a phone, the menu carries it

Every track, album and artist name in the app navigates through
`utils/explore-link.ts`, and every sentence of how it does that is a
desktop compromise: the navigation is held for one double-click
interval so double-clicking the row can still play it, and the target
is a few characters of text inside a row. On touch that is a delay on
an ambiguous target, and since #63 the row's own tap claims the click
anyway -- so the link was unreachable as well as fiddly.

So below the phone breakpoint a name renders as plain text and the
row's context menu carries the destination instead: `go-to-menu.ts`
draws "Go to Artist" / "Go to Album" under exactly the condition the
link is not, using `explore-link`'s own exported routing so an untagged
entity reaches the library page by the same lookup.

Three things this leans on. Suppressing a link with no menu behind it
is not a smaller affordance but a destination the phone cannot reach,
so `keepOnPhone` is the exception for the three surfaces with no row
menu. The items are drawn for a single selection only, which is the
Play item's rule one step on. And there is no "Go to Genre", because
no row renders a genre link to lose -- that would be new navigation
rather than a replacement.

Closes #67

frontend/src/utils/go-to-menu.ts

@@ -0,0 +1,109 @@
+/**
+ * "Go to Artist" / "Go to Album", for the menus that carry a name the
+ * phone stopped drawing as a link (#67).
+ *
+ * `utils/explore-link.ts` renders a plain string below the phone
+ * breakpoint, because a few characters inside a row is not a touch
+ * target and the row's own tap already means "play".  That takes a
+ * destination away, so the row's context menu gives it back — which is
+ * the whole of this issue: the navigation moves, it does not go.
+ *
+ * Three things about it are load-bearing.
+ *
+ * **It is drawn under exactly the condition the link is not.**
+ * `inlineLinksSuppressed()` answers both, so a desktop menu is
+ * untouched (the name beside it is still a link, and a menu that
+ * repeats what the row already offers is furniture) and a phone menu
+ * cannot be missing what the row lost.
+ *
+ * **It goes where the name went.** `openArtistPage` / `openAlbumPage`
+ * are `explore-link`'s own routing, exported rather than reimplemented,
+ * so an untagged artist reaches the library page here for the same
+ * reason and by the same lookup it does from a link.
+ *
+ * **The host says when it is over**, through `onSelect` — every menu in
+ * this app closes itself and most clear their selection, and both are
+ * the host's bookkeeping rather than something a shared item may do on
+ * its behalf.  `onHover` is for the four hosts with a playlist submenu,
+ * which closes on any other item being pointed at.
+ */
+
+import { html, nothing } from 'lit';
+import type { TemplateResult } from 'lit';
+
+import { inlineLinksSuppressed, openArtistPage, openAlbumPage } from './explore-link';
+
+/**
+ * The entities one row or card can send you to.
+ *
+ * Everything is optional because the hosts differ: a track row knows
+ * both, an album card knows only its artist, and an artist page's own
+ * tracklist knows only the album.
+ */
+export interface GoToTarget {
+    artistName?: string;
+    artistMBID?: string;
+    albumName?: string;
+    albumMBID?: string;
+}
+
+export interface GoToHandlers {
+    /** Called before navigating: close the menu, clear the selection. */
+    onSelect?: () => void;
+    /** Called on hover: close a playlist submenu, where the host has one. */
+    onHover?: () => void;
+}
+
+/**
+ * The menu items for a target, or nothing at all where the name beside
+ * them is still a link.
+ */
+export function goToMenuItems(
+    target: GoToTarget | undefined,
+    handlers: GoToHandlers = {},
+): TemplateResult | typeof nothing {
+    if (!target || !inlineLinksSuppressed()) return nothing;
+
+    const artist = target.artistName?.trim();
+    const album = target.albumName?.trim();
+
+    if (!artist && !album) return nothing;
+
+    return html`
+        ${artist
+            ? html`<wa-dropdown-item
+                  data-testid="go-to-artist"
+                  @click=${(e: Event) => {
+                      handlers.onSelect?.();
+                      void openArtistPage(
+                          e.currentTarget as EventTarget,
+                          artist,
+                          target.artistMBID ?? '',
+                      );
+                  }}
+                  @mouseenter=${() => handlers.onHover?.()}
+              >
+                  <wa-icon slot="icon" name="user-group"></wa-icon>
+                  Go to Artist
+              </wa-dropdown-item>`
+            : nothing}
+        ${album
+            ? html`<wa-dropdown-item
+                  data-testid="go-to-album"
+                  @click=${(e: Event) => {
+                      handlers.onSelect?.();
+                      void openAlbumPage(
+                          e.currentTarget as EventTarget,
+                          album,
+                          target.albumMBID ?? '',
+                          artist,
+                      );
+                  }}
+                  @mouseenter=${() => handlers.onHover?.()}
+              >
+                  <wa-icon slot="icon" name="compact-disc"></wa-icon>
+                  Go to Album
+              </wa-dropdown-item>`
+            : nothing}
+    `;
+}