feat(web/m7-364): queue mutations + drawer state on player store

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

web/src/lib/player/store.svelte.ts

@@ -27,6 +27,7 @@ let _volume   = $state(readStoredVolume());
 let _shuffle  = $state(false);
 let _repeat   = $state<RepeatMode>('off');
 let _error    = $state<string | null>(null);
+let _queueDrawerOpen = $state(false);
 
 // M4c: track when the queue was seeded by a radio call so we can
 // auto-refresh at 80% consumption. Cleared when the user enqueues
@@ -47,7 +48,8 @@ export const player = {
   get volume()    { return _volume; },
   get shuffle()   { return _shuffle; },
   get repeat()    { return _repeat; },
-  get error()     { return _error; }
+  get error()     { return _error; },
+  get queueDrawerOpen()   { return _queueDrawerOpen; }
 };
 
 export function registerAudioEl(el: HTMLAudioElement | null): void {
@@ -243,6 +245,70 @@ export async function playRadio(seedTrackId: string): Promise<void> {
   _radioSeedId = seedTrackId;  // M4c: set AFTER playQueue (which clears it)
 }
 
+export function moveQueueItem(from: number, to: number): void {
+  if (from === to) return;
+  if (from < 0 || from >= _queue.length) return;
+  if (to < 0 || to >= _queue.length) return;
+  const playingId = _queue[_index]?.id;
+  const next = _queue.slice();
+  const [moved] = next.splice(from, 1);
+  next.splice(to, 0, moved);
+  _queue = next;
+  if (playingId) {
+    const found = next.findIndex((x) => x.id === playingId);
+    if (found >= 0) _index = found;
+  }
+}
+
+export function removeFromQueue(idx: number): void {
+  if (idx < 0 || idx >= _queue.length) return;
+  const next = _queue.slice();
+  next.splice(idx, 1);
+  if (idx < _index) {
+    _queue = next;
+    _index = _index - 1;
+    return;
+  }
+  if (idx > _index) {
+    _queue = next;
+    return;
+  }
+  // idx === _index — removing the currently-playing track.
+  _queue = next;
+  if (next.length === 0) {
+    _index = 0;
+    _state = 'idle';
+    _position = 0;
+    _duration = 0;
+    _error = null;
+    return;
+  }
+  // _index stays — now points at what was the next track.
+  if (_index >= next.length) _index = next.length - 1;
+  _position = 0;
+  _duration = 0;
+  _state = 'loading';
+  _error = null;
+}
+
+export function playFromQueueIndex(idx: number): void {
+  if (idx < 0 || idx >= _queue.length) return;
+  _radioSeedId = null;
+  _index = idx;
+  _position = 0;
+  _duration = 0;
+  _state = 'loading';
+  _error = null;
+}
+
+export function toggleQueueDrawer(): void {
+  _queueDrawerOpen = !_queueDrawerOpen;
+}
+
+export function closeQueueDrawer(): void {
+  _queueDrawerOpen = false;
+}
+
 // M4c: auto-refresh radio queue when 80% consumed.
 // Fires whenever the consumption ratio crosses 80% AND the queue was
 // seeded by playRadio() AND no refresh is currently in-flight.