chore(app-server): add experimental annotation to relevant fields (#10928)

These fields had always been documented as experimental/unstable with
docstrings, but now let's actually use the `experimental` annotation to
be more explicit.

- thread/start.experimentalRawEvents
- thread/resume.history
- thread/resume.path
- thread/fork.path
- turn/start.collaborationMode
- account/login/start.chatgptAuthTokens

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

@@ -832,16 +832,6 @@
         "null"
       ]
     },
-    "history": {
-      "description": "[UNSTABLE] FOR CODEX CLOUD - DO NOT USE. If specified, the thread will be resumed with the provided history instead of loaded from disk.",
-      "items": {
-        "$ref": "#/definitions/ResponseItem"
-      },
-      "type": [
-        "array",
-        "null"
-      ]
-    },
     "model": {
       "description": "Configuration overrides for the resumed thread, if any.",
       "type": [
@@ -855,13 +845,6 @@
         "null"
       ]
     },
-    "path": {
-      "description": "[UNSTABLE] Specify the rollout path to resume from. If specified, the thread_id param will be ignored.",
-      "type": [
-        "string",
-        "null"
-      ]
-    },
     "personality": {
       "anyOf": [
         {