First release of the Sanitized AI extension for Firefox (v0.4.8.2).

Sanitized AI is an enterprise data loss prevention tool. On the AI chat and AI
search sites your organisation guards, it checks the prompt (and any attached
file) against your company's policy before it is sent, then allows, warns, or
blocks according to that policy.

In this version:
- Full Firefox (Gecko) support: MV3 event page, promise-based browser.* APIs,
and a Firefox-specific manifest build.
- Prompt scanning and file attachment scanning on 20 supported AI sites.
- In-page warning banner with re-edit, sanitize, and report-a-false-positive
actions, rendered in a shadow root so it cannot be styled or read by the page.
- Cookieless, token-bound sessions: the access token is bound to a
non-extractable ECDSA key, so a copied token cannot be replayed.
- Enterprise policy support via policies.json
(policies.3rdparty.Extensions.extension@sanitized.ai).
- English and Canadian French UI.

Known limitations on Firefox in this version:
- Sign-in is email and password only. Magic-link and SSO (Google, Microsoft,
Okta) are Chromium-only for now and are not available on Firefox.
- Desktop Firefox only. Firefox for Android is not supported.

The extension does nothing until a user signs in with their work account, and
runs only on the sites listed in host_permissions.