feat: Add curated plugin marketplace + Metadata Cleanup. (#13712)

1. Add a synced curated plugin marketplace and include it in marketplace
discovery.
2. Expose optional plugin.json interface metadata in plugin/list
3. Tighten plugin and marketplace path handling using validated absolute
paths.
4. Let manifests override skill, MCP, and app config paths.
5. Restrict plugin enablement/config loading to the user config layer so
plugin enablement is at global level

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

@@ -1,13 +1,118 @@
 {
   "$schema": "http://json-schema.org/draft-07/schema#",
   "definitions": {
+    "AbsolutePathBuf": {
+      "description": "A path that is guaranteed to be absolute and normalized (though it is not guaranteed to be canonicalized or exist on the filesystem).\n\nIMPORTANT: When deserializing an `AbsolutePathBuf`, a base path must be set using [AbsolutePathBufGuard::new]. If no base path is set, the deserialization will fail unless the path being deserialized is already absolute.",
+      "type": "string"
+    },
+    "PluginInterface": {
+      "properties": {
+        "brandColor": {
+          "type": [
+            "string",
+            "null"
+          ]
+        },
+        "capabilities": {
+          "items": {
+            "type": "string"
+          },
+          "type": "array"
+        },
+        "category": {
+          "type": [
+            "string",
+            "null"
+          ]
+        },
+        "composerIcon": {
+          "anyOf": [
+            {
+              "$ref": "#/definitions/AbsolutePathBuf"
+            },
+            {
+              "type": "null"
+            }
+          ]
+        },
+        "defaultPrompt": {
+          "type": [
+            "string",
+            "null"
+          ]
+        },
+        "developerName": {
+          "type": [
+            "string",
+            "null"
+          ]
+        },
+        "displayName": {
+          "type": [
+            "string",
+            "null"
+          ]
+        },
+        "logo": {
+          "anyOf": [
+            {
+              "$ref": "#/definitions/AbsolutePathBuf"
+            },
+            {
+              "type": "null"
+            }
+          ]
+        },
+        "longDescription": {
+          "type": [
+            "string",
+            "null"
+          ]
+        },
+        "privacyPolicyUrl": {
+          "type": [
+            "string",
+            "null"
+          ]
+        },
+        "screenshots": {
+          "items": {
+            "$ref": "#/definitions/AbsolutePathBuf"
+          },
+          "type": "array"
+        },
+        "shortDescription": {
+          "type": [
+            "string",
+            "null"
+          ]
+        },
+        "termsOfServiceUrl": {
+          "type": [
+            "string",
+            "null"
+          ]
+        },
+        "websiteUrl": {
+          "type": [
+            "string",
+            "null"
+          ]
+        }
+      },
+      "required": [
+        "capabilities",
+        "screenshots"
+      ],
+      "type": "object"
+    },
     "PluginMarketplaceEntry": {
       "properties": {
         "name": {
           "type": "string"
         },
         "path": {
-          "type": "string"
+          "$ref": "#/definitions/AbsolutePathBuf"
         },
         "plugins": {
           "items": {
@@ -28,7 +133,7 @@
         {
           "properties": {
             "path": {
-              "type": "string"
+              "$ref": "#/definitions/AbsolutePathBuf"
             },
             "type": {
               "enum": [
@@ -52,6 +157,22 @@
         "enabled": {
           "type": "boolean"
         },
+        "id": {
+          "type": "string"
+        },
+        "installed": {
+          "type": "boolean"
+        },
+        "interface": {
+          "anyOf": [
+            {
+              "$ref": "#/definitions/PluginInterface"
+            },
+            {
+              "type": "null"
+            }
+          ]
+        },
         "name": {
           "type": "string"
         },
@@ -61,6 +182,8 @@
       },
       "required": [
         "enabled",
+        "id",
+        "installed",
         "name",
         "source"
       ],