fix(mobile): route terminal taps without opening the keyboard

[Lint111]

Summary

Make terminal touches behave predictably on mobile without opening the software keyboard for TUI-owned content.

This PR is the focused tap/gesture slice extracted from the larger mobile-experience branch. It is intentionally limited to terminal-ui.js and its unit/browser regressions.

Behavior

• Treat the first tap that opens the keyboard as focus-only, so it cannot also activate the currently highlighted CLI option.
• Distinguish editable prompt rows from terminal content such as readbacks, tool results, permission choices, and status rows.
• Forward content taps to Claude/Codex/Gemini as SGR mouse reports while keeping the keyboard closed.
• Keep visible prompt taps focused on xterm's helper textarea.
• Keep local scrollback taps inert while the user is reading history.
• Recognize wrapped Claude Working / background-agent status rows as TUI content.
• Forward touch drags to Claude's own transcript on verified Claude versions while retaining xterm-local scrolling for Codex and other modes.
• Keep the live cursor and a small lower-screen input band focusable when a Claude redraw temporarily omits its prompt glyph.

Audit Fixes

The original classifier relied too heavily on visible prompt glyphs. During promptless Claude redraws, a live row could be classified as content, touchstart would suppress browser focus, and the mobile keyboard became unreachable.

The final commit gives precedence to known menus and working rows, then treats the live cursor and a four-row lower-screen fallback band as input. The browser regression verifies both required outcomes:

• xterm's helper textarea becomes document.activeElement
• no SGR mouse report is sent

The split also removes a hidden dependency on the separate history-anchor feature by using the existing local-scroll operations directly.

Commit Structure

1. fix(mobile): keep keyboard focus taps non-activating
2. fix(mobile): route terminal content taps to the CLI
3. fix(mobile): route Claude terminal gestures
4. fix(mobile): keep promptless terminal input focusable

Verification

• npx vitest run --config config/vitest.config.ts test/terminal-touch-tap.test.ts
  • 25 passed
• npx vitest run --config test/mobile/vitest.config.ts test/mobile/keyboard.test.ts -t "focuses the live Claude cursor|prevents Claude subagent status taps|focuses the terminal helper textarea when the visible prompt is tapped"
  • 3 passed, 32 skipped
• Additional focused mobile browser checks:
  • readback collapse
  • prompt focus
  • local touch scroll
  • Claude transcript drag
• npm run check:frontend-syntax
• npm run check:public-assets
• npx prettier --check test/mobile/keyboard.test.ts test/terminal-touch-tap.test.ts
• npm run build

Non-Goals

• Mobile virtual navigation controls and hardware volume-key fallback
• Centralized IME, paste, draft, or delivery state
• PTY viewport sizing ownership
• Terminal history streaming, compression, caching, or frame reconciliation