feat: verify Turborepo pipeline — all 8 packages build and test

Adds packageManager field to root package.json (required by turbo v2.9),
loads .env via dotenv in API jest config so Prisma integration tests find
DATABASE_URL when run from the monorepo root. pnpm build + pnpm test: 8/8 passing.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

pnpm-lock.yaml

@@ -69,6 +69,9 @@ importers:
       '@types/node':
         specifier: ^22.0.0
         version: 22.19.19
+      dotenv:
+        specifier: ^17.4.2
+        version: 17.4.2
       jest:
         specifier: ^29.0.0
         version: 29.7.0(@types/node@22.19.19)(ts-node@10.9.2(@types/node@22.19.19)(typescript@5.9.3))
@@ -1857,6 +1860,10 @@ packages:
     resolution: {integrity: sha512-k8DaKGP6r1G30Lx8V4+pCsLzKr8vLmV2paqEj1Y55GdAgJuIqpRp5FfajGF8KtwMxCz9qJc6wUIJnm053d/WCw==}
     engines: {node: '>=12'}
 
+  dotenv@17.4.2:
+    resolution: {integrity: sha512-nI4U3TottKAcAD9LLud4Cb7b2QztQMUEfHbvhTH09bqXTxnSie8WnjPALV/WMCrJZ6UV/qHJ6L03OqO3LcdYZw==}
+    engines: {node: '>=12'}
+
   dunder-proto@1.0.1:
     resolution: {integrity: sha512-KIN/nDJBQRcXw0MLVhZE9iQHmG68qAVIBg9CqmUYjmQIhgij9U5MFvrqkUL5FbtyyzZuOeOt0zdeRe4UY7ct+A==}
     engines: {node: '>= 0.4'}
@@ -5320,6 +5327,8 @@ snapshots:
 
   dotenv@17.4.1: {}
 
+  dotenv@17.4.2: {}
+
   dunder-proto@1.0.1:
     dependencies:
       call-bind-apply-helpers: 1.0.2