fix(docker): remove nx prune step that overwrites esbuild package.json

The `pnpm nx prune backend` step was overwriting esbuild's
generatePackageJson output with incorrect dependencies (build tools
instead of runtime deps like express, cors, etc.), causing
`npm install` to install the wrong packages.

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

Author: junzero741

apps/backend/Dockerfile

@@ -21,11 +21,9 @@ COPY packages/shared/ ./packages/shared/
 RUN cd apps/backend && npx prisma generate
 
 # Build backend (includes shared)
+# generatePackageJson in esbuild creates the correct runtime package.json
 RUN pnpm nx build backend
 
-# Prune lockfile + copy workspace modules for production install
-RUN pnpm nx prune backend
-
 # --- Production stage ---
 FROM node:22-slim
 

apps/backend/start.sh

@@ -1,16 +1,5 @@
 #!/bin/sh
 set -e
-
-echo "=== DEBUG: package.json ==="
-cat package.json
-echo ""
-echo "=== DEBUG: node_modules contents ==="
-ls node_modules/ 2>/dev/null | head -30
-echo ""
-echo "=== DEBUG: express resolve test ==="
-node -e "try { console.log('express at:', require.resolve('express')); } catch(e) { console.log('FAIL:', e.message); }"
-echo "=== END DEBUG ==="
-
 echo "Running migrations..."
 npx prisma migrate deploy
 echo "Starting server..."