fix(tui): disable mouse capture to restore native text selection

[coder-movers]

What

Stop enabling mouse capture when the TUI starts (and when it is reactivated after a handoff). Terminal-native drag-to-select and copy work again while the TUI is running.

Why

TuiTerminal::new and activate_best_effort in src/cli/tui/terminal.rs run EnableMouseCapture alongside EnterAlternateScreen. While capture is active the terminal emulator forwards mouse events to the process instead of performing native selection, so users could not select or copy any on-screen text from within the TUI.

The scroll-wheel-to-arrow mapping that previously consumed those events was already removed in ff9dfb2 (fix(tui): prevent long-list scroll stalls), so EnableMouseCapture now has no consumer yet still blocks selection. This PR drops the capture calls from the terminal enter/restore paths.

Why not keep capture and implement in-app selection instead: an app-drawn selection highlight is just rendered cells, not the terminal's selection, so Ctrl+C / Ctrl+Shift+C would still copy nothing useful. The app would have to write the clipboard itself (a new dependency or per-OS shell-out, with WSL2 needing clip.exe). Terminal-native selection is the only way to get copy via the terminal's existing keybindings without that cost, and it requires capture off.

Closes #347.

Change

• src/cli/tui/terminal.rs: remove the crossterm::event::{DisableMouseCapture, EnableMouseCapture} import and the four EnableMouseCapture / DisableMouseCapture arguments from the execute! calls in new, restore_stdout_best_effort, restore_best_effort, and activate_best_effort. EnterAlternateScreen / LeaveAlternateScreen, raw mode, and cursor show/hide are unchanged.

No change to mod.rs or tests.rs is needed on top of main: the Event::Mouse arm and the MouseEventKind import in mod.rs were already removed by ff9dfb2, and tests.rs already imports MouseEventKind directly.

Tradeoff

This is the opposite direction from #342, which requests mouse click support and needs EnableMouseCapture kept. Under crossterm, capture is all-or-nothing: in-app click hit-testing and terminal-native selection cannot coexist. This PR prioritizes copy-paste; if #342 is implemented later it should be opt-in rather than the default, or accept that selection is unavailable while active.

Testing

cd src-tauri && cargo test --lib cli::tui
# 1316 passed; 0 failed

cargo fmt --check is clean.