Expose plugin manifest keywords in app server (#21271)

## Summary
- Add plugin manifest keywords to core plugin marketplace/detail models
- Expose keywords on app-server v2 PluginSummary and generated
schema/types
- Populate keywords in plugin/list and plugin/read responses for local
plugins

Depends on https://github.com/openai/openai/pull/891087

## Validation
- just fmt
- just write-app-server-schema
- cargo test -p codex-app-server-protocol
- cargo test -p codex-core-plugins
- cargo test -p codex-app-server
plugin_list_keeps_valid_marketplaces_when_another_marketplace_fails_to_load
- cargo test -p codex-app-server
plugin_read_returns_plugin_details_with_bundle_contents

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

@@ -12710,6 +12710,13 @@
               }
             ]
           },
+          "keywords": {
+            "default": [],
+            "items": {
+              "type": "string"
+            },
+            "type": "array"
+          },
           "name": {
             "type": "string"
           },

codex-rs/app-server-protocol/schema/json/codex_app_server_protocol.v2.schemas.json

@@ -9321,6 +9321,13 @@
             }
           ]
         },
+        "keywords": {
+          "default": [],
+          "items": {
+            "type": "string"
+          },
+          "type": "array"
+        },
         "name": {
           "type": "string"
         },

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

@@ -347,6 +347,13 @@
             }
           ]
         },
+        "keywords": {
+          "default": [],
+          "items": {
+            "type": "string"
+          },
+          "type": "array"
+        },
         "name": {
           "type": "string"
         },

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

@@ -366,6 +366,13 @@
             }
           ]
         },
+        "keywords": {
+          "default": [],
+          "items": {
+            "type": "string"
+          },
+          "type": "array"
+        },
         "name": {
           "type": "string"
         },

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

@@ -307,6 +307,13 @@
             }
           ]
         },
+        "keywords": {
+          "default": [],
+          "items": {
+            "type": "string"
+          },
+          "type": "array"
+        },
         "name": {
           "type": "string"
         },

codex-rs/app-server-protocol/schema/typescript/v2/PluginSummary.ts

@@ -11,4 +11,4 @@ export type PluginSummary = { id: string, name: string, source: PluginSource, in
 /**
  * Availability state for installing and using the plugin.
  */
-availability: PluginAvailability, interface: PluginInterface | null, };
+availability: PluginAvailability, interface: PluginInterface | null, keywords: Array<string>, };