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).
This commit is contained in:
