Monorepo skeleton, Prisma schema, core domain and services with tests

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

.gitignore

@@ -0,0 +1,11 @@
+node_modules
+dist
+.next
+.turbo
+coverage
+*.log
+.env
+.env.*
+!.env.example
+.DS_Store
+packages/db/src/generated