feat(server): improve context metadata & matching (#12064)

fix AI-20

<!-- This is an auto-generated comment: release notes by coderabbit.ai -->
## Summary by CodeRabbit

- **New Features**
  - Enhanced file metadata with MIME type, blob ID, and file name across context and workspace, now visible in UI and API.
  - Added workspace-level matching for files and documents with configurable thresholds and workspace scoping in search queries.
  - Introduced a new error type and user-friendly messaging for global workspace context matching failures.

- **Bug Fixes**
  - Improved consistent handling of file MIME types and nullable context IDs for accurate metadata.

- **Documentation**
  - Updated GraphQL schema, queries, and mutations to include new metadata fields, optional parameters, and error types.

- **Style**
  - Added new localization strings for global context matching error messages.

- **Tests**
  - Extended test coverage with new and updated snapshot tests for metadata and matching logic.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

packages/frontend/i18n/src/i18n.gen.ts

@@ -8412,6 +8412,13 @@ export function useAFFiNEI18N(): {
         contextId: string;
         message: string;
     }>): string;
+    /**
+      * `Failed to match context in workspace {{workspaceId}} with "%7B%7Bcontent%7D%7D": {{message}}`
+      */
+    ["error.COPILOT_FAILED_TO_MATCH_GLOBAL_CONTEXT"](options: Readonly<{
+        workspaceId: string;
+        message: string;
+    }>): string;
     /**
       * `Embedding feature is disabled, please contact the administrator to enable it in the workspace settings.`
       */

packages/frontend/i18n/src/resources/en.json

@@ -2081,6 +2081,7 @@
   "error.COPILOT_CONTEXT_FILE_NOT_SUPPORTED": "File {{fileName}} is not supported to use as context: {{message}}",
   "error.COPILOT_FAILED_TO_MODIFY_CONTEXT": "Failed to modify context {{contextId}}: {{message}}",
   "error.COPILOT_FAILED_TO_MATCH_CONTEXT": "Failed to match context {{contextId}} with \"%7B%7Bcontent%7D%7D\": {{message}}",
+  "error.COPILOT_FAILED_TO_MATCH_GLOBAL_CONTEXT": "Failed to match context in workspace {{workspaceId}} with \"%7B%7Bcontent%7D%7D\": {{message}}",
   "error.COPILOT_EMBEDDING_DISABLED": "Embedding feature is disabled, please contact the administrator to enable it in the workspace settings.",
   "error.COPILOT_EMBEDDING_UNAVAILABLE": "Embedding feature not available, you may need to install pgvector extension to your database",
   "error.COPILOT_TRANSCRIPTION_JOB_EXISTS": "Transcription job already exists",