Mark Config.apps as experimental, correct schema generation issue (#10938)

This PR makes `Config.apps `experimental-only and fixes a TS schema
post-processing bug that removed needed imports. The bug happened
because import pruning only checked the inner type body after filtering,
not the full alias, so `JsonValue` got dropped from `Config.ts`. We now
prune against the full alias body and added a regression test for this
scenario.

codex-rs/app-server-protocol/schema/json/codex_app_server_protocol.schemas.json

@@ -10518,17 +10518,6 @@
               }
             ]
           },
-          "apps": {
-            "anyOf": [
-              {
-                "$ref": "#/definitions/v2/AppsConfig"
-              },
-              {
-                "type": "null"
-              }
-            ],
-            "default": null
-          },
           "compact_prompt": {
             "type": [
               "string",

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

@@ -78,17 +78,6 @@
             }
           ]
         },
-        "apps": {
-          "anyOf": [
-            {
-              "$ref": "#/definitions/AppsConfig"
-            },
-            {
-              "type": "null"
-            }
-          ],
-          "default": null
-        },
         "compact_prompt": {
           "type": [
             "string",