Middle-click paste (X11 primary selection) broken since v1.0.11

## Description

Middle-click paste (X11 primary selection) stopped working in the Copilot CLI chat prompt starting in v1.0.11. It works correctly in v1.0.3.

## Environment

- **OS:** SUSE Linux (kernel 5.14.21)
- **Terminal:** SSH session with X11 forwarding, TERM=xterm-color
- **Display:** X.Org X11
- **Works in:** v1.0.3
- **Broken in:** v1.0.11

## Steps to Reproduce

1. Connect via SSH with X11 forwarding
2. Launch Copilot CLI v1.0.11
3. Copy some text (select with mouse to populate X11 primary selection)
4. Middle-click in the chat prompt to paste
5. **Result:** Paste does not occur — the mouse event is captured by the app
6. **Expected:** Text should be pasted, as it does in v1.0.3

## Notes

- Shift+Middle-click works as a workaround (bypasses app mouse capture)
- Both versions tested in identical SSH sessions to the same machine, same terminal emulator, same TERM value, same X display
- The regression appears to be caused by a change in how mouse reporting/capture is handled between v1.0.3 and v1.0.11
- Sending escape sequences to disable mouse reporting (\e[?1000l etc.) from within the CLI does not help, as the app re-enables mouse capture on each prompt

## Workaround

Use Shift+Middle-click, or downgrade to v1.0.3.

Start by reproducing the issue in the chat prompt over SSH with X11 forwarding, then compare mouse reporting and capture behavior between v1.0.3 and v1.0.11. Trace the prompt's mouse handling and verify that ordinary middle-click pastes the X11 primary selection without requiring Shift.

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