refactor(player): E.34 — extract transport-light + undo/redo factories (#598)

Two small action-factory extractions in one PR, both following the
pattern from E.31–E.33.

- `createTransportLightActions` — `stop`, `pause`, `resetAudioPause`,
  `togglePlay`. Everything in the pause/togglePlay cluster except
  `resume` (~165 LOC, deferred to its own PR).
- `createUndoRedoActions` — `undoLastQueueEdit`, `redoLastQueueEdit`.
  Trivial wrappers around `applyQueueHistorySnapshot` + the queue-undo
  stack helpers.

Pure code-move. playerStore.ts: 1247 → 1167 LOC (−80).

src/store/transportLightActions.ts

@@ -0,0 +1,92 @@
+import { invoke } from '@tauri-apps/api/core';
+import { setIsAudioPaused } from './engineState';
+import type { PlayerState } from './playerStoreTypes';
+import { flushQueueSyncToServer } from './queueSync';
+import { pauseRadio, stopRadio } from './radioPlayer';
+import { clearAllPlaybackScheduleTimers } from './scheduleTimers';
+import { clearSeekDebounce } from './seekDebounce';
+import { clearSeekFallbackRetry } from './seekFallbackState';
+import { clearSeekTarget } from './seekTargetState';
+import { tryAcquireTogglePlayLock } from './togglePlayLock';
+
+type SetState = (
+  partial: Partial<PlayerState> | ((state: PlayerState) => Partial<PlayerState>),
+) => void;
+type GetState = () => PlayerState;
+
+/**
+ * Light transport actions factored out of the playerStore `create()`
+ * body — everything except `resume` (~165 LOC, separate PR) and the
+ * scheduled pause/resume timer setters.
+ *
+ *  - `stop` — full reset: stops audio/radio, clears timers + seek + visual
+ *    state, blanks playback metadata.
+ *  - `pause` — pauses audio (or radio), flushes queue position so other
+ *    devices can pick up the resume point.
+ *  - `resetAudioPause` — flips the engine-paused flag without touching
+ *    the UI `isPlaying` state. Used by `audio:ended` paths.
+ *  - `togglePlay` — guarded toggle so a double media-key tap can't race
+ *    pause + resume into a stuck state.
+ */
+export function createTransportLightActions(set: SetState, get: GetState): Pick<
+  PlayerState,
+  'stop' | 'pause' | 'resetAudioPause' | 'togglePlay'
+> {
+  return {
+    stop: () => {
+      clearAllPlaybackScheduleTimers();
+      if (get().currentRadio) {
+        stopRadio();
+      } else {
+        invoke('audio_stop').catch(console.error);
+      }
+      setIsAudioPaused(false);
+      clearSeekFallbackRetry();
+      clearSeekDebounce(); clearSeekTarget();
+      set({
+        isPlaying: false,
+        progress: 0,
+        buffered: 0,
+        currentTime: 0,
+        currentRadio: null,
+        waveformBins: null,
+        normalizationNowDb: null,
+        normalizationTargetLufs: null,
+        normalizationEngineLive: 'off',
+        currentPlaybackSource: null,
+        enginePreloadedTrackId: null,
+        scheduledPauseAtMs: null,
+        scheduledPauseStartMs: null,
+        scheduledResumeAtMs: null,
+        scheduledResumeStartMs: null,
+      });
+    },
+
+    pause: () => {
+      clearAllPlaybackScheduleTimers();
+      if (get().currentRadio) {
+        pauseRadio();
+      } else {
+        invoke('audio_pause').catch(console.error);
+        setIsAudioPaused(true);
+        // Flush position so a quick close after pause still leaves the
+        // server with the right resume point for other devices.
+        const s = get();
+        if (s.currentTrack) {
+          void flushQueueSyncToServer(s.queue, s.currentTrack, s.currentTime);
+        }
+      }
+      set({ isPlaying: false, scheduledPauseAtMs: null, scheduledPauseStartMs: null, scheduledResumeAtMs: null, scheduledResumeStartMs: null });
+    },
+
+    resetAudioPause: () => {
+      setIsAudioPaused(false);
+    },
+
+    togglePlay: () => {
+      if (!tryAcquireTogglePlayLock()) return;
+      const { isPlaying } = get();
+      isPlaying ? get().pause() : get().resume();
+    },
+  };
+}