Fix RSC toStringTag error: import PrismaClient from generated TS client

Use @/generated/prisma/client instead of @prisma/client to avoid
Turbopack creating a broken external proxy for the missing
.prisma/client/default module at runtime. Add @prisma/adapter-pg
to serverExternalPackages, remove unused resolveAlias.

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

src/lib/prisma.ts

@@ -1,4 +1,4 @@
-import { PrismaClient } from "@prisma/client";
+import { PrismaClient } from "@/generated/prisma/client";
 import { PrismaPg } from "@prisma/adapter-pg";
 
 const globalForPrisma = globalThis as unknown as {