Chromium extension MVP: rewrite selected text via local `personality-protect api`

[telivity-otaip]

Why

api.py already says it is "for a future browser extension." A minimal Chromium extension that calls loopback POST /v1/filter (and later /v1/write) is the most shareable demo of PersonalityProtect — and a magnet for stars, HN/Show HN comments, and extension-curious contributors.

MVP scope

New directory e.g. extensions/chromium/ (Manifest V3):

1. Toolbar popup: paste draft → Rewrite in my voice → show result
2. Talks only to http://127.0.0.1:8765 (configurable port)
3. Clear UX when API is down: "Start personality-protect api locally"
4. No account, no telemetry, no remote endpoints
5. Optional: right-click context menu on selected text

Depends on / pairs with the /v1/write API issue — MVP can ship against existing /v1/filter first.

Acceptance criteria

• Loadable unpacked in Chrome/Edge/Brave
• End-to-end against local personality-protect api with mock/demo profile
• README section: install extension + start API
• Privacy copy in the popup: corpus never leaves the machine
• No store listing required for MVP (unpacked is fine)
• Synthetic Contoso sample text only in screenshots/docs

Out of scope

• Firefox port (follow-up)
• Auto-posting to LinkedIn
• Cloud sync

Difficulty

Medium — small MV3 surface; huge marketing/traction upside.