Docs: sync with reality

README: storage is SQLite (aniweb.db), not JSON files; CDN serves a
single quality (no ABR) — replaced the wrong 1080/720/360 claim;
document the 16-lane parallel fetch, intro-skip, episode names,
buffering UI, /api/cdn + background probe, the ?v= cache-busting rule,
and the client self-report diagnostics.
SPEC: same single-rendition correction (2 places).
PLAN: marked complete (all items shipped; deferred list was stale).

PLAN.md

@@ -1,5 +1,9 @@
 # Plan — UI/UX polish bundle (items 1–4 + 7)
 
+**STATUS: complete** — every item below shipped (see git log, c2461f8 and
+friends). Kept as the planning record; the "deferred" list at the bottom
+is stale (favicon, a11y pass, autoplay-next were all done afterwards).
+
 The agreed bundle from the polish list:
 
 1. **Loading states** — skeleton cards + player spinner