feat: Add per-application filtering for key mappings

- Added AppFilterMode enum (all/exclude/include)
- Running apps list with bundle IDs in mapping editor
- Active app detection via NSWorkspace
- Filter logic in event tap callback
- Edit mapping functionality with persistent key capture
- Localized in 22 languages
- 4-column compact UI for app selection (900px wide)
- Debug logging for troubleshooting

Author: badcode64