[Bug] Mouse capture enabled by default breaks native terminal text selection and copy

Bug Description
Title: Mouse capture is on by default and silently breaks native terminal copy (⌘C / text selection)

Environment

• OS: macOS (Darwin 25.5)
• Terminal: [Terminal.app / iTerm2 — fill in]
• Claude Code version: [claude --version]
• Relevant setting: "tui": "fullscreen"

Summary
While Claude Code is running, the terminal's native click-drag text selection stops working, so ⌘C cannot copy and the terminal's Copy menu item is greyed out (no selection can be made). Quitting Claude Code immediately restores normal selection/copy. The cause is Claude Code
enabling terminal mouse reporting, which captures click-drag before the terminal can turn it into a selection.

Steps to reproduce

1. Start claude in a terminal.
2. Try to select output text by click-dragging, then ⌘C.
3. Observe: no selection forms; Edit → Copy is greyed out. (Paste/⌘V still works, since it needs no selection.)
4. Quit Claude → selection and ⌘C work normally again. Reproduces on every fresh Claude session.

Expected
Native text selection and copy keep working, or mouse capture is off by default.

Actual
Mouse capture is enabled by default, silently disabling copy. The only fix is CLAUDE_CODE_DISABLE_MOUSE=1, which is undiscoverable — nothing in the UI indicates mouse mode is on or how to bypass it.

Impact
Losing copy makes the tool feel broken — copying error text, paths, and snippets out of the session is a constant need. Users with no idea about the env var will conclude copy is simply broken.

Suggested fixes (any of)

• Default mouse capture to off, opt-in for those who want wheel-scroll/click.
• Show a one-time hint when mouse mode is active: "hold ⌥ Option (iTerm2) / Fn (Terminal.app) to select text," and surface the CLAUDE_CODE_DISABLE_MOUSE toggle.
• Add an in-app toggle / slash command (not just an env var requiring a restart).

Workaround for other users: set CLAUDE_CODE_DISABLE_MOUSE=1 (env or ~/.claude/settings.json → env), restart; or hold ⌥/Fn while dragging.

Environment Info

• Platform: darwin
• Terminal: Apple_Terminal
• Version: 2.1.173
• Feedback ID: 68953134-92c1-4d40-b35e-edd3ba067c2b

Errors

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