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.

core/prisma/tsconfig.json

@@ -0,0 +1,26 @@
+{
+  "extends": "../../tsconfig.base.json",
+  "compilerOptions": {
+    "composite": true,
+    "target": "es2017",
+    "module": "commonjs",
+    "moduleResolution": "node",
+    "outDir": "dist",
+    "declaration": true,
+    "emitDeclarationOnly": true,
+    "declarationDir": "dist",
+    // Overriding base to be specific for this package
+    "baseUrl": ".",
+    "paths": {} // Clear paths from base, not needed here
+  },
+  "include": ["./schema.prisma", "./generated/client", "index.ts", "client.ts"],
+  "exclude": [
+    "node_modules",
+    "dist",
+    ".next",
+    ".turbo",
+    "coverage",
+    "build",
+    "prisma/seed.ts"
+  ]
+}