feat: upgrade major dependencies to latest versions

- Prisma 6.19 → 7.7 (driver adapter pattern, prisma.config.ts)
- TypeScript 5.9 → 6.0 (ignoreDeprecations, CSS type declarations)
- Vitest 3.2 → 4.1
- Pino 9.14 → 10.3
- @types/node 22.x → 25.x

All 307 tests pass, typecheck clean, build succeeds.

Co-Authored-By: Paperclip <noreply@paperclip.ing>

scripts/seed-plans.ts

@@ -5,9 +5,13 @@
  * Idempotent: uses upsert on PlanTier unique constraint.
  */
 
+import { PrismaPg } from '@prisma/adapter-pg';
 import { PrismaClient, PlanTier } from '@prisma/client';
+import pg from 'pg';
 
-const prisma = new PrismaClient();
+const pool = new pg.Pool({ connectionString: process.env['DATABASE_URL'] });
+const adapter = new PrismaPg(pool);
+const prisma = new PrismaClient({ adapter });
 
 export const PLANS = [
   {