fix(web): scroll terminal output with touch gestures

[shivamhwp]

Closes #2141

Touch drags in the web terminal selected text instead of scrolling, leaving mobile browsers stuck at the newest output in #2141.

Route vertical touch drags through the terminal's existing wheel behavior. Scrollback moves in both directions, full-screen programs receive their existing scroll input, and taps still focus the terminal or open links. Pointer activation also selects the touched split pane.

59 focused terminal tests and web typecheck pass. Four new touch cases fail on the baseline; scoped lint reports seven existing drawer warnings. In the isolated Chromium client, the same gesture changes scrollback from 87 to 77 and back to 87 after the fix; it stays at 87 before. Tapping an inactive split selects and focuses it. Physical iOS/Android browsers, native mobile, and remote/relay sessions were not exercised. Web and desktop share this terminal; native mobile uses a separate client. There are no provider, wire-contract, or settings changes.

Stacked on #11298 so the current HTTP client migration typechecks. That PR retains its human authentication-review hold.

Before:

After:

Touch scrolling in both directions:

t3-2141-touch-scroll.mp4

Model: GPT-6. Harness: Codex in T3 Code.

[macroscopeapp]

Approvability

Verdict: Not approved

Macroscope's review found this PR not approvable — This PR adds default touch-gesture behavior to production terminal surfaces, including scrollback movement, terminal input reporting, link taps, and split-terminal activation. The interaction logic is localized and well-tested, but its user-facing event and input changes warrant human review.

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[github-actions]

Thread transfer impact

✅ Thread transfer remains within every enforced ceiling.

ℹ️ No successful main baseline artifact is available yet. This run establishes the initial measurement.

Provider	Metric	Main baseline	This PR	Impact	PR ceiling
Codex	Total thread wire	—	13.6 KiB	—	15.1 KiB	✅
Codex	Thread snapshot wire	—	7.0 KiB	—	7.3 KiB	✅
Codex	Live turn WebSocket wire	—	6.6 KiB	—	7.8 KiB	✅
Codex	Live turn WebSocket decoded	—	57.1 KiB	—	66.4 KiB	✅
Codex	Live turn messages	—	10	—	21	✅
Claude	Total thread wire	—	13.6 KiB	—	15.1 KiB	✅
Claude	Thread snapshot wire	—	7.1 KiB	—	7.3 KiB	✅
Claude	Live turn WebSocket wire	—	6.5 KiB	—	7.8 KiB	✅
Claude	Live turn WebSocket decoded	—	57.8 KiB	—	66.4 KiB	✅
Claude	Live turn messages	—	9	—	21	✅

Baseline: unavailable · PR result: d62b7a1 · 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: 113.9 KiB
• Claude decoded thread snapshot: 114.6 KiB

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