refactor: tidy the assistant transport and slim requestRaw

[caitlon]

Problem

requestRaw in lib/api.ts was above Sonar's cognitive complexity limit (17 of 15). A Retry-After sent as an HTTP date parsed to NaN. The assistant stream left an abort listener on the caller's signal after the request settled. A few review leftovers in the chat hook had no test that would catch their removal, and the composer textarea was 2 px short of its content, which shows a scrollbar on Windows from the second line.

Change

• requestRaw: the 401 refresh-and-retry branch moves to a private refreshOrExpire (17 -> 10). Behaviour unchanged.
• parseRetryAfter: delta-seconds as before, an HTTP date becomes the seconds until it, anything else is undefined, so a date value no longer reaches the assistant as NaN.
• The stream request removes its abort listener when it settles; the redundant pending.catch is gone.
• Chat hook: storage key versioned as assistant-chat:v1 (sign-out still clears every assistant-chat: key); one shared isRecord; a redundant array check in loadMessages and an extra write bump in restoreDraft removed (both covered by tests); expected refusals (404, 422, 429, 503) log as warnings, everything else as errors; tests that fail when either conversation-switch guard is removed.
• Composer height includes the border.

Verification

• npm run lint, npm run typecheck, npm run test:coverage (thresholds held).
• Complexity measured with eslint-plugin-sonarjs: requestRaw 17 -> 10, send 13 -> 10.

Migrations

None.

Screenshots

None.

[greptile-apps]

Automatic reviews are disabled for this repository.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
98.3% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud