Foundation slice of the browser-extension migration onto the typed-item
core from Plans 1A+1B. Scope: WASM artifact rebuild, typed-item shared
types, SessionHandle-based service worker, split router with sender
checks, full security architecture (origin-bound autofill, TOFU ack,
closed Shadow DOM, popup captured-tab verification), zxcvbn setup gate,
Login-parity popup. Other 6 item types land in 1C-β; attachments/trash/
history/device UI in 1C-γ.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
