chore: release 0.3.1 — iOS PWA fixes, notification improvements, docs update

- fix(pwa): iOS keyboard gap caused by WebKit viewport-fit=cover bug.
  After keyboard open/close, 100dvh permanently shrinks. Track max
  innerHeight in --app-height CSS variable as stable replacement.
- feat(pwa): auto-prompt notification permission on first login in
  standalone mode (once only, skips if denied).
- refactor: remove duplicate notification toggle from header menu
  (already in Settings).
- feat(dev): expose Vite dev server on network (host: true) for
  mobile testing via Tailscale.
- docs: update README — add Task Progress FAB, fix notification
  flow description, document OPENAI_API_KEY / VAPID_EMAIL env vars,
  clarify voice input backends, add CLI --version/--help, update
  .env.example.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/lib/storage-keys.ts

@@ -6,6 +6,7 @@ export const STORAGE = {
   DRAFT: 'clawtap:draft',
   INSTALL_DISMISSED: 'clawtap:install-dismissed',
   SESSIONS_TAB: 'clawtap:sessionsTab',
+  PUSH_PROMPTED: 'clawtap:push-prompted',
   adapterPrefs: (id: string) => `clawtap:adapterPrefs:${id}` as const,
 } as const;