[codex] Track plugin install and import telemetry failures (#28731)

## Summary
- Track plugin install failures through the unified
`codex_plugin_install_failed` event for local installs, remote install
preflight failures, bundle failures, and remote catalog/backend
failures.
- Send classified `error_type` values in plugin install failure
analytics instead of raw error strings.
- Stop sending raw external-agent import errors in analytics while
preserving raw failure details in app-facing import
notifications/history.
- Keep raw plugin/migration diagnostics in `tracing::warn!` logs.
- Keep remote failure plugin names as the existing local placeholder
(`unknown`) and remove the extra telemetry plugin-name override.
- Change `ExternalAgentConfigImportParams.source` from a generated enum
to `string | null`, with legacy `claudeCode` / `claudeCowork` inputs
normalized to existing analytics values.

## Testing

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

@@ -800,7 +800,7 @@
           ]
         },
         "includeHome": {
-          "description": "If true, include detection under the user's home (~/.claude, ~/.codex, etc.).",
+          "description": "If true, include detection under the user's home directory.",
           "type": "boolean"
         }
       },
@@ -813,6 +813,13 @@
             "$ref": "#/definitions/ExternalAgentConfigMigrationItem"
           },
           "type": "array"
+        },
+        "source": {
+          "description": "Source product that produced the migration items. Missing means unspecified.",
+          "type": [
+            "string",
+            "null"
+          ]
         }
       },
       "required": [

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

@@ -9119,7 +9119,7 @@
             ]
           },
           "includeHome": {
-            "description": "If true, include detection under the user's home (~/.claude, ~/.codex, etc.).",
+            "description": "If true, include detection under the user's home directory.",
             "type": "boolean"
           }
         },
@@ -9282,6 +9282,13 @@
               "$ref": "#/definitions/v2/ExternalAgentConfigMigrationItem"
             },
             "type": "array"
+          },
+          "source": {
+            "description": "Source product that produced the migration items. Missing means unspecified.",
+            "type": [
+              "string",
+              "null"
+            ]
           }
         },
         "required": [

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

@@ -5404,7 +5404,7 @@
           ]
         },
         "includeHome": {
-          "description": "If true, include detection under the user's home (~/.claude, ~/.codex, etc.).",
+          "description": "If true, include detection under the user's home directory.",
           "type": "boolean"
         }
       },
@@ -5567,6 +5567,13 @@
             "$ref": "#/definitions/ExternalAgentConfigMigrationItem"
           },
           "type": "array"
+        },
+        "source": {
+          "description": "Source product that produced the migration items. Missing means unspecified.",
+          "type": [
+            "string",
+            "null"
+          ]
         }
       },
       "required": [

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

@@ -12,7 +12,7 @@
       ]
     },
     "includeHome": {
-      "description": "If true, include detection under the user's home (~/.claude, ~/.codex, etc.).",
+      "description": "If true, include detection under the user's home directory.",
       "type": "boolean"
     }
   },

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

@@ -184,6 +184,13 @@
         "$ref": "#/definitions/ExternalAgentConfigMigrationItem"
       },
       "type": "array"
+    },
+    "source": {
+      "description": "Source product that produced the migration items. Missing means unspecified.",
+      "type": [
+        "string",
+        "null"
+      ]
     }
   },
   "required": [

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

@@ -4,7 +4,7 @@
 
 export type ExternalAgentConfigDetectParams = {
 /**
- * If true, include detection under the user's home (~/.claude, ~/.codex, etc.).
+ * If true, include detection under the user's home directory.
  */
 includeHome?: boolean,
 /**

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

@@ -3,4 +3,8 @@
 // This file was generated by [ts-rs](https://github.com/Aleph-Alpha/ts-rs). Do not edit this file manually.
 import type { ExternalAgentConfigMigrationItem } from "./ExternalAgentConfigMigrationItem";
 
-export type ExternalAgentConfigImportParams = { migrationItems: Array<ExternalAgentConfigMigrationItem>, };
+export type ExternalAgentConfigImportParams = { migrationItems: Array<ExternalAgentConfigMigrationItem>,
+/**
+ * Source product that produced the migration items. Missing means unspecified.
+ */
+source?: string | null, };