fix: exclude prisma.config.ts from TS compilation, use datasource.url

prisma.config.ts is a Prisma CLI config file, not part of the Next.js
app — exclude it from tsconfig to prevent type errors. Also revert the
migrate.adapter block (not a valid PrismaConfig key in 7.5) back to
datasource.url which is the correct CLI config for db push.

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

tsconfig.json

@@ -30,5 +30,5 @@
     ".next/dev/types/**/*.ts",
     "**/*.mts"
   ],
-  "exclude": ["node_modules"]
+  "exclude": ["node_modules", "prisma.config.ts"]
 }