Terminate Windows non-TTY processes on interrupt (#35655)

## Why

Windows non-TTY exec sessions reported interrupts as unsupported, so sending
Ctrl-C through `write_stdin` did not stop the running process.

## What changed

- Route interrupt requests for Windows non-TTY processes through their existing
  termination callback, including pipe-backed processes.
- Track whether driver-backed Windows sessions use a TTY so PTY interrupts keep
  their existing behavior.
- Consume the terminator after a successful interrupt to avoid invoking it again
  when the process handle is dropped.

## Testing

Added coverage for local and remote exec-server sessions, unified exec, pipe
fallbacks, and legacy Windows sandbox processes.

GitOrigin-RevId: 34504d01f091ef57bb961e98ad5a8d9f1acee4ee

codex-rs/exec-server/src/local_process.rs

@@ -1764,6 +1764,8 @@ mod tests {
             terminator: None,
             writer_handle: None,
             resizer: None,
+            #[cfg(windows)]
+            tty: false,
         })
         .session
     }