fix(memory): bound visualizer PCM cache and feed episode cache

The visualizer's PCM cache decoded the entire episode into RAM (22050 Hz
mono s16 ~160 MB/hr of audio) and held it until stop() — a 3-hour episode
pinned ~500 MB and long-form content hit 2.5 GB. The 4x decode also pulled
the whole remote file even when only minutes were listened to.

- audio-pcm-cache: sliding window around the playback position — the
  decode head caps at maxAheadSec (600s) ahead of the cursor, segments
  older than keepBehindSec (300s) are pruned, and the tail refills as
  playback advances. Steady state ~40 MB regardless of episode length;
  a backward seek past the window restarts a segment there (the existing
  seek-hole mechanism, no new failure mode).
- feed: cap the full-parse episode cache at 1000 episodes/feed so
  archive-heavy subscriptions can't pin their entire history in RAM;
  the visible list stays bounded by the user's cache preference and
  fetch-more keeps working within the ceiling.
- tests: pin the new head-cap and prune contracts (8/8 in
  audio-pcm-cache.test.ts; full suite 193 pass).

Also includes the in-flight cleanup/refactor pass (cover-art resolve
helper, page and comment tightening, ESLint config removal).

src/stores/search.ts

@@ -60,7 +60,6 @@ function saveScope(scope: SearchScope): void {
 	}
 }
 
-/** Create search store */
 export function createSearchStore() {
 	const feedStore = useFeedStore();
 	const [query, setQuery] = createSignal("");
@@ -167,7 +166,6 @@ export function createSearchStore() {
 		}
 	};
 
-	/** Add query to history */
 	const addToHistory = (q: string) => {
 		setHistory((prev) => {
 			const updated = sanitizeHistory([q, ...prev]);
@@ -176,13 +174,11 @@ export function createSearchStore() {
 		});
 	};
 
-	/** Clear search history */
 	const clearHistory = () => {
 		setHistory([]);
 		saveSearchHistoryToFile([]);
 	};
 
-	/** Remove single history item */
 	const removeFromHistory = (q: string) => {
 		setHistory((prev) => {
 			const updated = prev.filter((h) => h !== q);
@@ -191,14 +187,12 @@ export function createSearchStore() {
 		});
 	};
 
-	/** Clear results */
 	const clearResults = () => {
 		setResults([]);
 		setQuery("");
 		setError(null);
 	};
 
-	/** Mark a podcast as subscribed in results */
 	const markSubscribed = (podcastId: string, feedUrl?: string) => {
 		setResults((prev) =>
 			prev.map((result) => {
@@ -262,7 +256,6 @@ export function createSearchStore() {
 	};
 }
 
-/** Singleton search store */
 let searchStoreInstance: ReturnType<typeof createSearchStore> | null = null;
 
 export function useSearchStore() {