feat(library): play all and shuffle all on every track list

Four pages that list tracks — Tracks, genre, artist, and both playlist
views — had no way to start the whole list, or had a broken one. One
shared helper (utils/play-all.ts) now owns what "shuffle this
collection" means: SetQueue's shuffleStart only picks a random first
track when shuffle mode is already on, it does not turn it on, so the
mode is toggled before the queue is set. Each host passes an honest
queue Source (#14): anything that builds a queue names what it built it
from, so "Playing from" stops lying.

Two behaviour changes ride along, both flagged: smart-playlist-details'
Shuffle was a live no-op (shuffleStart without enabling mode played
track 1 in order) and is fixed; playlist-details' Play all drops its
shuffleStart:true, so with shuffle mode already on it now starts at the
first row instead of a random one — the album page's existing
semantics.

Verified: make ui-test (1147, incl. a case that fails when the
smart-playlist fix is reverted), npx tsc --noEmit, make e2e (255,
incl. new play-all and header-fit specs), make lint, make test,
make bindings-check, make css-check; artist header read from
screenshots at 424/320/900 (the pair wraps below the name on a phone).

Closes #31

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

@@ -11,11 +11,22 @@ import {
     GetArtistImageCachedPath,
     GetArtistMBID,
 } from '@go/explore/service.js';
+import { GetFilePathsByAlbums } from '@go/library/library.js';
+import { libraryStore } from '@store/library-store';
+import { notificationStore } from '@store/notification-store';
+import { dict } from '@utils/binding';
+import { playAll } from '@utils/play-all';
+import { describeError } from '@utils/describe-error';
+import { ICON_PLAY, ICON_SHUFFLE } from '@utils/icon-language';
 import '@awesome.me/webawesome/dist/components/icon/icon.js';
 import '@components/cover-grid/cover-grid.js';
+import '../notifications/inline-notice';
 import { designTokens } from '../../styles/tokens.css';
 import { backButton } from '../../styles/back-button.css';
 
+/** The region the artist header's own failures are rendered in. */
+const ArtistRegion = 'library-artist';
+
 @customElement('artist-details')
 export class ArtistDetails extends LitElement {
     @property({ type: Number, attribute: 'artist-id' })
@@ -131,6 +142,39 @@ export class ArtistDetails extends LitElement {
             );
         }
 
+        .header-actions {
+            margin-left: auto;
+            display: flex;
+            align-items: center;
+            gap: 8px;
+            flex-shrink: 0;
+        }
+
+        .header-action {
+            background: none;
+            border: 1px solid var(--yj-border-subtle, #555);
+            border-radius: 4px;
+            color: var(--yj-text-primary, #fff);
+            padding: 6px 12px;
+            font-size: var(--yj-text-md, 13px);
+            font-family: inherit;
+            cursor: pointer;
+            display: flex;
+            align-items: center;
+            gap: 6px;
+            white-space: nowrap;
+        }
+
+        .header-action:hover {
+            border-color: var(--yj-accent, #ffd43b);
+            color: var(--yj-accent-text, #ffd43b);
+        }
+
+        .header-action:disabled {
+            opacity: 0.5;
+            cursor: default;
+        }
+
         /* ====================================
          * Content
          * ==================================== */
@@ -145,6 +189,23 @@ export class ArtistDetails extends LitElement {
             height: 100%;
         }
 
+        /* Phone widths: the header's flex row squeezed .artist-info to
+         * nothing, so the title ellipsised away entirely and the
+         * actions clipped against the host's own overflow — the album
+         * page's fault one detail view over (#66). The pair takes its
+         * own row instead. Written last, because a media query adds no
+         * specificity and a rule placed above the plain ones it
+         * overrides is silently dead. */
+        @media (max-width: 599px) {
+            .artist-header {
+                flex-wrap: wrap;
+            }
+
+            .header-actions {
+                flex-basis: 100%;
+                margin-left: 0;
+            }
+        }
     `];
 
     override connectedCallback() {
@@ -302,6 +363,45 @@ export class ArtistDetails extends LitElement {
         return name.charAt(0).toUpperCase();
     }
 
+    /**
+     * Play every track on this artist's albums, in album order.
+     *
+     * One `GetFilePathsByAlbums` call returns the paths grouped by
+     * album id; the caller owns the ordering, so they are flattened in
+     * `this.albums` order rather than by id.
+     */
+    private async playAllTracks(shuffle: boolean): Promise<void> {
+        if (this.albums.length === 0) return;
+
+        try {
+            const libId = libraryStore.getSelectedLibraryId() ?? 0;
+            const ids = this.albums.map((a) => a.ID);
+            const byAlbum = await dict(
+                GetFilePathsByAlbums(ids, libId),
+            );
+            const paths: string[] = [];
+
+            for (const id of ids) {
+                paths.push(...(byAlbum[id] ?? []));
+            }
+
+            playAll(
+                paths,
+                {
+                    type: 'artist',
+                    id: this.artistId,
+                    label: this.artistName,
+                },
+                shuffle,
+            );
+        } catch (error) {
+            console.error('Could not play artist:', error);
+            notificationStore.inline(ArtistRegion, {
+                text: describeError(error, 'Could not play this artist’s tracks.'),
+            });
+        }
+    }
+
     /* ================================================================
      * Rendering
      * ================================================================ */
@@ -351,12 +451,38 @@ export class ArtistDetails extends LitElement {
                           `
                         : ''}
                 </div>
+                <div class="header-actions">
+                    <button
+                        class="header-action"
+                        data-testid="artist-play-all"
+                        ?disabled=${this.albums.length === 0}
+                        @click=${() =>
+                            void this.playAllTracks(false)}
+                    >
+                        <wa-icon name=${ICON_PLAY}></wa-icon>
+                        Play all
+                    </button>
+                    <button
+                        class="header-action"
+                        data-testid="artist-shuffle-all"
+                        ?disabled=${this.albums.length === 0}
+                        @click=${() =>
+                            void this.playAllTracks(true)}
+                    >
+                        <wa-icon name=${ICON_SHUFFLE}></wa-icon>
+                        Shuffle all
+                    </button>
+                </div>
             </div>
             <div class="content">
                 <cover-grid
                     .externalAlbums=${this.albums}
                 ></cover-grid>
             </div>
+            <inline-notice
+                region=${ArtistRegion}
+                testid="artist-play-message"
+            ></inline-notice>
         `;
     }
 }