Fix: add node_modules symlinks for module resolution

Dockerfile

@@ -2,7 +2,7 @@ FROM node:20-slim
 
 ENV DEBIAN_FRONTEND=noninteractive
 
-# Build timestamp: 2026-01-13T03:45
+# Build timestamp: 2026-01-13T04:00
 
 WORKDIR /app
 
@@ -25,6 +25,12 @@ RUN esbuild backend/src/server.ts --bundle --platform=node --target=node20 --for
     --outfile=backend/dist/backend/src/server.js \
     --external:express --external:socket.io --external:cors --external:dotenv --external:uuid
 
+# Create symlinks so node can find modules from deep paths
+RUN ln -s /app/node_modules /app/backend/node_modules && \
+    ln -s /app/node_modules /app/backend/dist/node_modules && \
+    ln -s /app/node_modules /app/backend/dist/backend/node_modules && \
+    ln -s /app/node_modules /app/backend/dist/backend/src/node_modules
+
 # Copy frontend dist
 COPY trigo-web/app/dist/ ./app/dist/