## Summary
- Add keybinding preset system: save, load, switch, import, export, and
delete named keybinding sets stored via `/api/userdata/keybindings/`
- Preset selector dropdown with "Save Changes" button for modified
custom presets, and "Import keybinding preset" action
- More-options menu in header row with save as new, reset, delete,
import, and export actions
- Search box and menu teleported to settings dialog header (matching
templates modal layout)
- 11 unit tests for preset service CRUD operations
Fixes#1084Fixes#1085
## Test plan
- [ ] Open Settings > Keybinding, verify search box and "..." menu
appear in header
- [ ] Modify a keybinding, verify "Default *" shows modified indicator
- [ ] Use "Save as new preset" from menu, verify preset appears in
dropdown
- [ ] Switch between presets, verify unsaved changes prompt
- [ ] Export preset, import it back, verify bindings restored
- [ ] Delete a custom preset, verify reset to default
- [ ] Verify "Save Changes" button appears only on modified custom
presets
- [ ] Run `pnpm vitest run
src/platform/keybindings/presetService.test.ts`
┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-9681-feat-import-export-keybinding-presets-31e6d73d3650810f88e4d21b3df3e2dd)
by [Unito](https://www.unito.io)
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Co-authored-by: GitHub Action <action@github.com>
