docs(bridge): update types + docs for set_display_layout configStr

- Add set_display_layout (+ other missing system handler methods) to
  AetherNativeBridge interface in types.ts
- README: clarify configStr source (event_device.data_json) and
  no-op behaviour when absent
- TODO_AGENTS: correct 7z→bsdtar throughout; mark Electron-side
  set_display_layout items done; remove completed bsdtar doc item

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

README.md

@@ -240,7 +240,7 @@ to change.
 | `window_control({action, value?})` | Electron window: maximize, minimize, restore, close, fullscreen, kiosk, devtools, reload. |
 | `set_wallpaper({path})` | Sets desktop wallpaper. macOS (AppleScript) + Linux (gsettings/Gnome). |
 | `power_control({action})` | Shutdown, reboot, or sleep. macOS + Linux. Requires sudo for shutdown/reboot. |
-| `set_display_layout({mode, configStr?})` | Mirror/extend displays via bundled `displayplacer` binary. macOS only. |
+| `set_display_layout({mode, configStr?})` | Mirror/extend displays via bundled `displayplacer` binary. macOS only. `configStr` is the output of `displayplacer list` for that machine, stored in `event_device.data_json.displayplacer_config_mirror` / `displayplacer_config_extend`. Required — silently no-ops without it. |
 | `manage_recording({action, options?})` | Screen recording via bundled `aperture` binary. macOS only. |
 | `update_app(args)` | **Stub.** Downloads update package but does not install. Not functional. |
 | `list_tools()` | Returns a self-describing manifest of all available bridge functions. |