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/ui/command.tsx

@@ -156,9 +156,6 @@ function init() {
 				setRegistrations((arr) => arr.filter((x) => x !== results));
 			});
 		},
-		/**
-		 * Get all visible options.
-		 */
 		get options() {
 			return visibleOptions();
 		},
@@ -195,9 +192,6 @@ export function CommandProvider(props: ParentProps) {
 	return <ctx.Provider value={value}>{props.children}</ctx.Provider>;
 }
 
-/**
- * Command palette dialog component.
- */
 function CommandDialog(props: {
 	options: CommandOption[];
 	suggestedOptions: CommandOption[];

src/ui/dialog.tsx

@@ -98,9 +98,6 @@ function init() {
   })
 
   return {
-    /**
-     * Clear all dialogs from the stack.
-     */
     clear() {
       for (const item of store.stack) {
         if (item.onClose) item.onClose()
@@ -113,9 +110,6 @@ function init() {
       emit("dialog.close", {})
     },
 
-    /**
-     * Replace all dialogs with a new one.
-     */
     replace(input: JSX.Element | (() => JSX.Element), onClose?: () => void) {
       if (store.stack.length === 0) {
         focus = renderer.currentFocusedRenderable
@@ -130,9 +124,6 @@ function init() {
       emit("dialog.open", { dialogId: "dialog" })
     },
 
-    /**
-     * Push a new dialog onto the stack.
-     */
     push(input: JSX.Element | (() => JSX.Element), onClose?: () => void) {
       if (store.stack.length === 0) {
         focus = renderer.currentFocusedRenderable
@@ -143,9 +134,6 @@ function init() {
       emit("dialog.open", { dialogId: "dialog" })
     },
 
-    /**
-     * Pop the top dialog from the stack.
-     */
     pop() {
       if (store.stack.length === 0) return
       const current = store.stack.at(-1)!