fix(web): detect software keyboard before handling composer Enter

[Yash-Singh1]

A narrow or zoomed desktop window disabled every composer send shortcut because the composer used viewport width to identify mobile input. It could also blur the editor after sending with a hardware keyboard.

Use software keyboard visibility instead. Web reads VirtualKeyboard geometry when supplied and falls back to Ionic's zoom-aware viewport detection. Electron bypasses detection. Plain Return inserts a newline while the software keyboard is open, modifier shortcuts remain available, and sending only blurs the editor when the software keyboard is open.

Validation: 118 focused unit tests passed, along with targeted lint, formatting, and the web typecheck. Physical mobile keyboard behavior has not been device-tested.

Implemented with GPT 6.1 Sol through the Codex harness.

Fixes #16396

[macroscopeapp]

Approvability

Verdict: Needs Human Approval

Macroscope's review found this PR requires human approval — This PR changes production composer Enter, submission, and focus behavior using a new cross-browser software-keyboard detector. The logic is isolated and well covered by unit tests, but physical mobile keyboard behavior remains unvalidated, warranting human review.

Notes:

• Diff unchanged. Approvability was decided on eligibility alone.

^{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	5.0 KiB	5.0 KiB	0 B (0.0%)	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	0 B (0.0%)	2.0 KiB	✅
Codex	Live turn WebSocket decoded	20.9 KiB	20.9 KiB	0 B (0.0%)	29.3 KiB	✅
Codex	Live turn messages	2	2	0 (0.0%)	8	✅
Claude	Total thread wire	5.0 KiB	5.0 KiB	0 B (0.0%)	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	0 B (0.0%)	2.0 KiB	✅
Claude	Live turn WebSocket decoded	21.2 KiB	21.2 KiB	0 B (0.0%)	29.3 KiB	✅
Claude	Live turn messages	2	2	0 (0.0%)	8	✅

Baseline: 7e7e6d8 · PR result: 4b4ab57 · 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.