Refactor: Centralize Prisma schema and restrict DB access

This commit refactors the project to use a shared Prisma schema and restricts direct database access to the API service.

Key changes:

- Created a new shared package `core/prisma` containing the Prisma schema, generated client, and types.
- Configured the monorepo to use NPM workspaces, including `core/prisma` and all services.
- Updated all services (`api`, `ui`, `mcp`, `agent`, and the background processing service) to depend on `@empresa/prisma-schema`.
- The API service now imports `PrismaClient` from `@empresa/prisma-schema/client`.
- Other services import only types from `@empresa/prisma-schema`.
- Removed redundant Prisma configurations from `api` and the background processing service.
- Updated the background processing service's `sync-empleados.js` to fetch data via an API call instead of direct database access.
- Updated TypeScript configurations (`tsconfig.base.json` and service-specific ones) to support the new structure and path aliases.
- Updated `README.md` to reflect the new architecture and added convenience scripts for Prisma operations.

This change promotes a single source of truth for data models, reduces code duplication, and improves the overall architecture by centralizing database operations within the API service.

agent/package.json

@@ -15,6 +15,7 @@
     "@open-wa/wa-automate": "^4.34.3",
     "mime-types": "^2.1.35",
     "@modelcontextprotocol/sdk": "^1.0.0",
-    "@philschmid/weather-mcp": "^1.0.0"
+    "@philschmid/weather-mcp": "^1.0.0",
+    "@empresa/prisma-schema": "1.0.0"
   }
 }