feat: support disable skills by name. (#15378)

Support disabling skills by name, primarily for plugin skills. We can’t
use the path, since plugin skill paths may change across versions.

codex-rs/app-server-protocol/schema/json/ClientRequest.json

@@ -2343,13 +2343,27 @@
         "enabled": {
           "type": "boolean"
         },
+        "name": {
+          "description": "Name-based selector.",
+          "type": [
+            "string",
+            "null"
+          ]
+        },
         "path": {
-          "type": "string"
+          "anyOf": [
+            {
+              "$ref": "#/definitions/AbsolutePathBuf"
+            },
+            {
+              "type": "null"
+            }
+          ],
+          "description": "Path-based selector."
         }
       },
       "required": [
-        "enabled",
-        "path"
+        "enabled"
       ],
       "type": "object"
     },