[FEATURE]: Title: Allow remapping or disabling Ctrl+C to prevent accidental thread loss

Feature hasn't been suggested before.

• I have verified this feature I'm about to request hasn't been suggested before.

Describe the enhancement you want to request

Ctrl+C currently interrupts the current generation and drops to a debug prompt. When pasting with Ctrl+V, it's easy to accidentally hit Ctrl+C instead, which loses the entire thread.
Request: Add a config option (e.g. in opencode.json) to remap or disable the Ctrl+C interrupt binding. For example:
{
"keybind": {
"interrupt": "disabled"
}
}
Or allow remapping to a different key combination like Ctrl+Shift+C.
Use case: Prevent accidental thread loss when pasting (Ctrl+V) and the finger slips to Ctrl+C.