FIX: Remove .env file dependency from Docker build

- Remove COPY .env ./.env from Dockerfile
- Container now relies on AutoSSLSetup to generate .env at runtime
- Eliminates build-time dependency on auto-generated files
- Enables true zero-config container deployment

🤖 Generated with [Claude Code](https://claude.ai/code)

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

docker/Dockerfile

@@ -87,7 +87,6 @@ COPY --from=native-builder /app/node_modules /app/node_modules
 COPY --from=backend-builder /app/dist/backend ./dist/backend
 
 COPY package.json ./
-COPY .env ./.env
 RUN chown -R node:node /app
 
 VOLUME ["/app/data"]