- Rename extension to "Outcut" throughout all source files and console logs
- Add KEY_PRESETS object (gmail/outlook) and matchesAction() helper to keyboard.js
- Rewrite handleKeydown to use preset-based dispatch instead of hardcoded switch
- Update updateSettings to re-init when keyboardPreset changes
- Add keyboardPreset: 'gmail' default to settings-defaults.js
- Replace popup Design Tweaks UI with preset dropdown + dynamic help text
- Keep all design tweak content script logic intact (activatable via storage)
- Update manifest: version 1.0.0, remove activeTab, add homepage_url
