Fix TypeScript build issues in backend

- Remove prisma/seed.ts from tsconfig include (outside rootDir)
- Use direct path to tsc binary instead of npx
- npx tsc was installing wrong package (tsc@2.0.4)
- Fixes TS6059 error about rootDir

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

Author: roberteinsle

apps/backend/Dockerfile

@@ -56,7 +56,7 @@ RUN npm run prisma:generate --workspace=apps/backend && \
 ENV NODE_ENV=build
 RUN echo "Starting TypeScript build..." && \
     cd apps/backend && \
-    npx tsc && \
+    ../../node_modules/.bin/tsc && \
     echo "✓ TypeScript build completed" && \
     ls -la dist/
 ENV NODE_ENV=production

apps/backend/tsconfig.json

@@ -8,6 +8,6 @@
     "rootDir": "./src",
     "types": ["node"]
   },
-  "include": ["src/**/*", "prisma/seed.ts"],
-  "exclude": ["node_modules", "dist"]
+  "include": ["src/**/*"],
+  "exclude": ["node_modules", "dist", "prisma"]
 }