ci: fix two main-branch vitest failures

[kalvinnchau]

Summary

Two independent failures landed on main simultaneously and broke the vitest job:

1. src/app/App.profile.test.tsx (4 failures + 4 unhandled errors): AppShell reads window.matchMedia (Polish top bar and animate contextual sidebar toggle #360) but jsdom has no media queries; the test file from feat(shell): open your profile from the account menu avatar #390 never stubbed it, so the app render crashed (TypeError: window.matchMedia is not a function) and every query found an empty <body>. Fix: stub matchMedia in the fixture (same as feat: add inbox conversations and draft previews #422's 87a808e / feat(native): serve relay media and uploads in packaged builds #433's f300a5e).

2. src/features/messages/ChannelTimeline.restore.test.tsx (converged / removed cases): merge race between flake fix: keep restored reading anchor out of bottom follow (WebKit scroll measurement) #407 and Improve member and agent identity previews #412 — flake fix: keep restored reading anchor out of bottom follow (WebKit scroll measurement) #407's guard if (anchor) position.bottom = false was validated against a tree without Improve member and agent identity previews #412's tests, and it suppresses bottom follow whenever a restored anchor exists, including Improve member and agent identity previews #412's legitimate settled/superseded cases. Fix (cherry-picked from feat(native): serve relay media and uploads in packaged builds #433's 2806fc0 + e80f60d, authorship preserved): retire the restored anchor once it has genuinely settled (rendered at its saved Y, not clamped, not a membership group) or been replaced by a visible row, and keep flake fix: keep restored reading anchor out of bottom follow (WebKit scroll measurement) #407's suppression only while the restoration is still live (if (restoredAnchor.current)). e80f60d also fixes an optional-chaining crash when position.anchor is undefined. This is strictly more faithful to flake fix: keep restored reading anchor out of bottom follow (WebKit scroll measurement) #407's WebKit fix than a first-observation-only gate: every non-input scroll through estimated heights stays excluded from bottom follow until real convergence.

Test plan

• vitest run src/app/App.profile.test.tsx src/features/messages/ChannelTimeline.restore.test.tsx src/features/messages/ChannelTimeline.test.tsx — 104 passed (all previously failing tests included)
• biome check on changed files
• Full vitest run in CI

[wesbillman]

Carl, an automated reviewer, commenting via Wes’s GitHub account.

No blocking findings in this focused review.

Reviewed head 72a041120cf5e0a552c317dfcf285b105c6451d2 against base 6b0730cf9b14b3af0a45574834d7eb8f71a45f31. Traced restoration recording, deferred correction/cleanup, reader overrides, and membership-group identity preservation. The profile fixture stub matches the shell’s media-query API and is cleaned up after each test. Existing restoration tests cover repeated cold clamps, convergence, removed anchors, and explicit input.

Validation: source/test review and clean diff check; no local suites or browser runs repeated. JavaScript and browser checks, including the WebKit cold-reload measurement, are still running at review time. Those remain the integration gate; this comment is not approval or a claim of native validation.