feat(server): basic mcp server (#13298)

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

* **New Features**
* Introduced a new endpoint for MCP (Model Context Protocol) server
interaction under `/api/workspaces/:workspaceId/mcp`, enabling advanced
document reading and search capabilities within workspaces.
* Added support for semantic and keyword search tools, as well as
document reading through the MCP server, with user access control and
input validation.

* **Improvements**
* Enhanced metadata handling in semantic search results for improved
clarity.
* Streamlined internal imports and refactored utility functions for
better maintainability.

* **Chores**
  * Added a new SDK dependency to the backend server package.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

packages/backend/server/package.json

@@ -40,6 +40,7 @@
     "@fal-ai/serverless-client": "^0.15.0",
     "@google-cloud/opentelemetry-cloud-trace-exporter": "^2.4.1",
     "@google-cloud/opentelemetry-resource-util": "^2.4.0",
+    "@modelcontextprotocol/sdk": "^1.16.0",
     "@nestjs-cls/transactional": "^2.6.1",
     "@nestjs-cls/transactional-adapter-prisma": "^1.2.19",
     "@nestjs/apollo": "^13.0.4",