Make provider-owned terminal cards read-only for user input while
preserving local inspection. This builds on the explicit terminal
ownership introduced in #64544.

- Add a construction-time `TerminalView::with_read_only` option,
selected from ACP process ownership rather than PTY presence. Existing
views remain interactive by default, including client-owned headless
terminals.
- Reject typing, send actions, paste, file/path drops, IME input,
clear/rerun actions, and focus reports in read-only views.
- Preserve selection, copying, links, scrolling, search, and local Vi
navigation. Leaving Vi mode does not enable terminal input.
- Pass an explicit mouse-routing policy to the existing lower terminal
handlers so provider-requested mouse and alternate-scroll modes cannot
consume inspection gestures. Real modifiers remain unchanged, and
Linux/FreeBSD middle-click paste is suppressed.

Release Notes:

- N/A