refactor(web/auth): extract user state to break auth<->player cycle (B2)

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

@@ -1,7 +1,7 @@
 import type { TrackRef, RadioResponse } from '$lib/api/types';
 import { untrack } from 'svelte';
 import { api } from '$lib/api/client';
-import { user } from '$lib/auth/store.svelte';
+import { user } from '$lib/auth/user.svelte';
 import { readPersistedQueue, writePersistedQueue } from './persisted';
 
 export type PlayerState = 'idle' | 'loading' | 'playing' | 'paused' | 'error';
@@ -397,10 +397,7 @@ $effect.root(() => {
   // queue/index changes drive it. The throttled-write effect below
   // covers position drift.
   $effect(() => {
-    // `user?.value` (not `user.value`) guards against module-init order during
-    // tests: auth/store.svelte.ts imports from this file, so when this module
-    // loads via that chain, `user` may not yet be assigned. See I2 follow-up.
-    const userId = user?.value?.id;
+    const userId = user.value?.id;
     if (!userId) return;
     // Reading these registers the reactive dependency; the values
     // themselves are unused — writePersistedQueue re-reads live state.
@@ -416,7 +413,7 @@ $effect.root(() => {
 
   // Throttled write on position changes.
   $effect(() => {
-    const userId = user?.value?.id;
+    const userId = user.value?.id;
     if (!userId) return;
     const _p = _position;
     void _p;