fix(web): filter a refetched mix inside the self-heal step, not by wrapping the closure (#5418)

The wrapper added a promise hop, so the self-heal test's single
microtask wait saw 'loading' instead of 'error'.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

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

@@ -144,8 +144,7 @@ export function playQueue(
   // rotation-aware order, so no client shuffle in that path).
   _queueSource = opts.source ?? null;
   // #968: a fresh play replaces the self-heal closure + resets its budget.
-  const refetch = opts.refetch;
-  _queueRefetch = refetch ? () => refetch().then(playable) : null;
+  _queueRefetch = opts.refetch ?? null;
   _selfHealAttempts = 0;
   // Start on the chosen track's place in the playable list; if the chosen
   // one is missing, that place holds the next playable track after it.
@@ -376,7 +375,8 @@ function trySelfHeal(): boolean {
   _error = null;
   const refetch = _queueRefetch;
   void refetch()
-    .then((refs) => {
+    .then((fetched) => {
+      const refs = playable(fetched);
       if (refs.length > 0) {
         // Re-seed in place — keep _queueSource / _queueRefetch so the new
         // snapshot can itself self-heal, and don't reset _selfHealAttempts