Project switcher in popup, pending-recording composer, cursor-crop video ...

- Popup: project dropdown (list_projects + settings_save defaultProjectId);
  switching refreshes the last-report card and panel link immediately.
- Recording stop no longer submits blindly: the buffer goes pending and a
  composer opens in the tab with title (prefilled) + description, Save
  (Ctrl+Enter, copies the share link) or two-step Discard; unanswered
  pending recordings auto-save after 10 minutes, and starting a new
  recording auto-saves a pending one. Composer survives navigation.
- WebM is now a square cursor-following crop (shared cursorCropRect helper
  with the GIF path), source dimension raised to 1280 so the 512px crop is
  native-resolution at DPR 1; full-frame 800px stays as fallback.
- e2e: second project + popup switcher asserts, composer save (typed
  title/description verified on server), keyboard-driven discard flow,
  ffprobe square-video assertions (512x512 VP8).

Co-Authored-By: Claude Code <noreply@anthropic.com>

Extension: picker, note composer, recorder + infra (Makefile, prod compose, README) ...

- MV3 extension for Chrome and Firefox: single codebase, per-entry IIFE
  builds (background / content / options), manifests generated per target
- Background service worker owns all networking (Bearer token from
  storage.local), captureVisibleTab (windowId!), recorder event buffer
  with offset_ms and auto-screenshots on clicks
- Content overlay in a closed shadow root (constructable stylesheets,
  kit CSS fetched from assets/style.css with /assets URL rewrite);
  PickerLayer, NoteComposer (autofocus, Ctrl+Enter submit),
  RecorderBar (step counter, note, stop)
- Options page: server URL, login, default project
- Recorder steps link screenshots by uploaded file id (server accepts
  attachment id or file id); environment/element JSONB serialized with
  mode="json" (datetime captured_at broke inserts)
- e2e harness: headless Chromium + extension, note + recording flows
- Makefile, docker-compose.prod.yml (caddy :8081 + static panel),
  deploy/Caddyfile, README (ru) with extension install and /assets notes

Co-Authored-By: Claude Code <noreply@anthropic.com>