feat: add typescript monorepo with pnpm workspaces and prisma database package

- root package.json + pnpm-workspace.yaml + tsconfig.base.json
- packages/types: canonical enums (TenantStatus, AgentState)
- packages/shared: re-exports types, base for future utilities
- packages/database: Prisma 7 schema with driver adapter (pg), initial
  tenants table matching agente.md section 29, first migration applied

pnpm-workspace.yaml

@@ -0,0 +1,9 @@
+packages:
+  - "apps/*"
+  - "packages/*"
+allowBuilds:
+  '@prisma/engines': true
+  esbuild: false
+  msgpackr-extract: false
+  prisma: true
+  workerd: false