fix(mobile,web): adopt upstream small fixes

[rynfar]

Second PR of the 9b2d04317..b883fc066 batch. Four clean upstream picks plus one branding fix. No native rebuild.

• #8914 mobile — draft navigation waits for submission to settle instead of racing the usePreventRemove guard
• #9102 web — the selected environment survives a project change
• #8889 web — expand/collapse all on the files surface
• #8500 web — toggling advanced colors preserves the theme

Branding

#9102 carried "T3 Code selects another environment that has the project" into docs/user/composer.md. That's product copy in a user-facing doc, not a compatibility identifier, so it's rebranded in a separate commit. docs/user/composer.md is back to zero T3 Code references.

That's the third such leak this batch — after the microphone permission string and two doc lines in the last one. Worth noting the pattern: they arrive in docs/user/ prose attached to otherwise-clean code fixes, so they survive typecheck and lint. I now grep every + line for T3 Code before pushing rather than relying on review.

Deliberately not in this PR

Two commits conflicted and were parked rather than hand-merged here, to keep this reviewable:

• #8922 (smooth worktree setup status) — 9 hunks across 5 web files including MessagesTimeline.tsx and session-logic.ts. It also supplies isWorktreeSetupActivity, a prerequisite for the mobile media chain, so it gets a focused PR.
• #8043 (dedupe skills in composer menus) — conflicts in Pylon's diverged composer menu.

Also skipped #8851: Pylon already shipped its sibling as d06520fc9.

Verification

@t3tools/web and @t3tools/mobile typecheck clean, lint 0 errors, 1714 mobile thread tests + 165 web component tests passing.

Reviewed and integrated with Claude Opus 5 in Claude Code.

---

^{Need help on this PR? Tag @codesmith-bot with what you need. Autofix is disabled.}

[github-actions]

Thread transfer impact

✅ Thread transfer remains within every enforced ceiling.

Provider	Metric	Main baseline	This PR	Impact	PR ceiling
Codex	Total thread wire	13.6 KiB	13.7 KiB	+169 B (+1.2%)	15.1 KiB	✅
Codex	Thread snapshot wire	6.9 KiB	6.9 KiB	−1 B (−0.0%)	7.3 KiB	✅
Codex	Live turn WebSocket wire	6.6 KiB	6.8 KiB	+170 B (+2.5%)	7.8 KiB	✅
Codex	Live turn WebSocket decoded	57.2 KiB	58.7 KiB	+1.5 KiB (+2.6%)	66.4 KiB	✅
Codex	Live turn messages	10	11	+1 (+10.0%)	21	✅
Claude	Total thread wire	13.6 KiB	13.7 KiB	+161 B (+1.2%)	15.1 KiB	✅
Claude	Thread snapshot wire	6.9 KiB	6.9 KiB	−1 B (−0.0%)	7.3 KiB	✅
Claude	Live turn WebSocket wire	6.7 KiB	6.8 KiB	+162 B (+2.4%)	7.8 KiB	✅
Claude	Live turn WebSocket decoded	58.1 KiB	59.5 KiB	+1.4 KiB (+2.4%)	66.4 KiB	✅
Claude	Live turn messages	11	11	0 (0.0%)	21	✅

Baseline: 8c329d0 · PR result: 0fc44e2 · Source CI: success

Scenario and decoded snapshot size

10 historical turns, 5 command tools per turn, 878.9 KiB retained MCP result per historical turn, and a 1.05 MiB retained result in the measured turn.

• Codex decoded thread snapshot: 109.5 KiB
• Claude decoded thread snapshot: 110.2 KiB

Updated in place by a trusted workflow. PR artifacts are strictly validated and never executed.