Add explicit prisma output path to fix Docker build

Without output directive, Prisma 7 generates to node_modules/@prisma/client
in the Docker build context, causing the @/generated/prisma/client import
to fail with "Module not found". Explicit output ensures generated TypeScript
files are always placed at src/generated/prisma/.

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

prisma/schema.prisma

@@ -1,5 +1,6 @@
 generator client {
   provider = "prisma-client-js"
+  output   = "../src/generated/prisma"
 }
 
 datasource db {