fix(permission): address PR review feedback

- Map ACP SDK options (optionId/name) to webview format (id/label)
- Fix field name mismatch: content → rawInput
- Handle malformed permissionResponse with else clause
- Check webview availability before posting permission request
- Validate empty options array and return cancelled immediately
- Store/clear timeout ID to prevent race condition
- Add Escape key handler to close modal
- Add backdrop click to close modal
- Focus first option button instead of modal container
- Restore focus to previously focused element when modal closes
- Replace inline onclick with addEventListener for cancel button

Author: omercnet