v0.53.0: Readiness report in exec mode and settings stability

New features

- /readiness-report in exec mode - Support for /readiness-report slash command in droid exec mode with optional custom instructions

Bug fixes

- Settings.json corruption prevention - Settings file now uses atomic writes to prevent corruption
- Terminal info disabled - Disabled getTerminalInfo to prevent issues
- Authentication stability - Bundled keychain dependency in packaged builds to reduce flaky sign-in setups