docs: refresh README's feature list and Coming Next; capture this session's hard-won lessons in CLAUDE.md

[schmitzkr]

Docs-only, no code changes.

README

• "What works today" was missing SSO sign-in, Browse (series/authors/
  shelves), Search, and in-app update checks entirely — all shipped in
  earlier PRs (feat: dashboard rows, browse and search, bookmarks, in-app updates #30, feat: SSO sign-in through the server's OIDC provider #31) but never documented here.
• The EPUB and comic/PDF reader bullets didn't mention this session's
  additions: two more reading themes (black, forest), edge-tap page
  turning, and tap-the-middle-to-hide-controls immersive reading.
• "Coming next" listed SSO sign-in, dashboard rows, series/authors/
  shelves, search, bookmarks and in-app updates — every single one of
  which has already shipped. Replaced with a pointer to the issue
  tracker instead of inventing a new speculative list.

CLAUDE.md

Added three conventions this session's debugging turned up the hard way,
so a future session doesn't rediscover them:

• The EPUB reader's WebView can't be trusted to report its own size or
  fire a resize event; Compose's own measured layout is the only
  reliable source, which is why reader.open()/reader.resize() take
  explicit width/height instead of reading window.innerWidth/innerHeight
  on the page side.
• Surface's automatic content-color inference silently breaks once its
  color param doesn't exactly equal a theme role color (e.g. one with a
  modified alpha) — pass contentColor explicitly instead of relying on
  it, especially under a nested MaterialTheme override.
• Never catch (e: Exception) around a suspend call that can be
  legitimately cancelled without rethrowing CancellationException first.

This is a docs-only change with no code touched, so no build/lint was run.

🤖 Generated with Claude Code