feat(mobile): redesign the Add environment sheet

[juliusmarminge]

The mobile Add environment sheet was a plain form with a hidden QR toggle in the header, and connecting gave no feedback until it finished or an error banner pushed the layout around.

What changed

• Scan card. Tapping the card asks for the camera, so opening the sheet never prompts. Once allowed, the live feed fills the card behind one continuous blur with a rounded, sharp cutout around the reticle. The blur is a small native view (T3FrostedCutoutView in t3-native-controls) that follows the app's light/dark theme. Android uses a tinted SVG cutout instead.
• Manual entry. Inline Address/Code rows with muted labels, aligned on a fixed row height. A pairing failure turns the card border red and replaces the footer note with the error, so nothing shifts. The error clears when you edit or leave.
• Submit. A header ✓ replaces the in-form button and shows a spinner while connecting. Header actions gained a generic loading flag (iOS via a new NativeHeaderToolbar.Custom item, Android in AndroidScreenHeader). Success and failure trigger haptics.
• T3 Connect. A new "Or use the managed relay" section reuses CloudEnvironmentRows when signed in and shows a sign-in row otherwise. Manual pairing copy now targets local network and Tailscale only.
• Removed the now-unused ConnectionSheetButton.

Requires a native rebuild (new iOS view). Verified on device by @juliusmarminge.

Done with Claude Opus 5.5 in Claude Code.

🤖 Generated with Claude Code

---

[macroscopeapp]

Approvability

Verdict: Not approved

Macroscope's review found this PR not approvable — This PR substantially redesigns the production Add environment workflow, adding QR scanning, native platform UI, authentication-aware managed relay behavior, and shared header infrastructure changes. Its new runtime paths and required native rebuild create a broader review surface than a routine UI-only change.

^{You can add or adjust custom eligibility rules. Learn more.}

[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	4.9 KiB	5.0 KiB	+23 B (+0.5%)	6.8 KiB	✅
Codex	Thread snapshot wire	3.8 KiB	3.8 KiB	0 B (0.0%)	4.9 KiB	✅
Codex	Live turn WebSocket wire	1.2 KiB	1.2 KiB	+23 B (+1.9%)	2.0 KiB	✅
Codex	Live turn WebSocket decoded	20.8 KiB	20.9 KiB	+41 B (+0.2%)	29.3 KiB	✅
Codex	Live turn messages	1	2	+1 (+100.0%)	8	✅
Claude	Total thread wire	5.0 KiB	5.0 KiB	−24 B (−0.5%)	6.8 KiB	✅
Claude	Thread snapshot wire	3.8 KiB	3.8 KiB	0 B (0.0%)	4.9 KiB	✅
Claude	Live turn WebSocket wire	1.2 KiB	1.2 KiB	−24 B (−2.0%)	2.0 KiB	✅
Claude	Live turn WebSocket decoded	21.2 KiB	21.2 KiB	−41 B (−0.2%)	29.3 KiB	✅
Claude	Live turn messages	2	1	−1 (−50.0%)	8	✅

Baseline: 73e097b · PR result: 5fff28a · 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: 108.5 KiB
• Claude decoded thread snapshot: 108.8 KiB

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