Expose disabled plugin settings in the app-server API (#44905)

## What changed

- Accept `disabledPluginIds` in `thread/settings/update` and `turn/start`. A supplied list replaces the saved selection; omission or `null` preserves it, and `[]` clears it.
- Return the selection in thread start, resume, and fork responses and `thread/settings/updated` notifications. Update generated schemas and client types.
- Restore disabled plugin IDs from the history retained at the requested fork boundary, preserving explicit overrides.

The selection persists across resume but does not yet filter plugin capabilities.

## Testing

Add coverage for replacing, preserving, and clearing selections without inference; turn-start notifications; resume; and fork boundaries across legacy and paginated history, with loaded and restarted parents. Add a core regression test for history restoration and explicit clearing.

GitOrigin-RevId: 654a8c2a0527228d422c0dd4919228447e2663db

codex-rs/app-server-protocol/schema/json/v2/ThreadStartResponse.json

@@ -2942,6 +2942,14 @@
     "cwd": {
       "$ref": "#/definitions/AbsolutePathBuf"
     },
+    "disabledPluginIds": {
+      "default": [],
+      "description": "Saved list of disabled plugin IDs. Does not yet filter plugin capabilities.",
+      "items": {
+        "type": "string"
+      },
+      "type": "array"
+    },
     "instructionSources": {
       "default": [],
       "description": "Environment-native paths to instruction source files currently loaded for this thread.",