feat: Add marketplace source filtering and plugin share context (#21419)

Adds marketplaceKinds to plugin/list for local, workspace-directory, and
shared-with-me; omitted params keep default local plus gated global
behavior, while explicit kinds are exact.

Exposes shareContext on plugin summaries from local share mappings and
remote workspace/shared responses, including remotePluginId and nullable
creator metadata.

Adds shared-with-me listing through /ps/plugins/workspace/shared,
renames the workspace remote namespace to workspace-directory, and keeps
direct remote read/share/install/update/delete paths gated by plugins
rather than remote_plugin.

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

@@ -8964,6 +8964,14 @@
       ],
       "type": "object"
     },
+    "PluginListMarketplaceKind": {
+      "enum": [
+        "local",
+        "workspace-directory",
+        "shared-with-me"
+      ],
+      "type": "string"
+    },
     "PluginListParams": {
       "$schema": "http://json-schema.org/draft-07/schema#",
       "properties": {
@@ -8976,6 +8984,16 @@
             "array",
             "null"
           ]
+        },
+        "marketplaceKinds": {
+          "description": "Optional marketplace kind filter. When omitted, only local marketplaces are queried, plus the default remote catalog when enabled by feature flag.",
+          "items": {
+            "$ref": "#/definitions/PluginListMarketplaceKind"
+          },
+          "type": [
+            "array",
+            "null"
+          ]
         }
       },
       "title": "PluginListParams",
@@ -9092,6 +9110,29 @@
       "title": "PluginReadResponse",
       "type": "object"
     },
+    "PluginShareContext": {
+      "properties": {
+        "creatorAccountUserId": {
+          "type": [
+            "string",
+            "null"
+          ]
+        },
+        "creatorName": {
+          "type": [
+            "string",
+            "null"
+          ]
+        },
+        "remotePluginId": {
+          "type": "string"
+        }
+      },
+      "required": [
+        "remotePluginId"
+      ],
+      "type": "object"
+    },
     "PluginShareDeleteParams": {
       "$schema": "http://json-schema.org/draft-07/schema#",
       "properties": {
@@ -9456,6 +9497,17 @@
         "name": {
           "type": "string"
         },
+        "shareContext": {
+          "anyOf": [
+            {
+              "$ref": "#/definitions/PluginShareContext"
+            },
+            {
+              "type": "null"
+            }
+          ],
+          "description": "Remote sharing context associated with this plugin when available."
+        },
         "source": {
           "$ref": "#/definitions/PluginSource"
         }