chore: reorganize Docker infrastructure into backend directory

Move Docker-related files into the backend directory to co-locate
infrastructure with the backend code:
- docker-compose.yml → backend/docker-compose.yml
- nginx.conf → backend/nginx.conf
- scripts/docker-build.sh → backend/docker-build.sh

Update all path references in:
- backend/README.md: Update build script path
- backend/docker-compose.yml: Update context and volume paths
- backend/docker-build.sh: Update package.json reference

This keeps backend infrastructure self-contained and makes the
deployment setup clearer.

Addresses PR #892 feedback.

Author: dannon

backend/README.md

@@ -26,11 +26,11 @@ API documentation: http://localhost:8000/api/docs
 
 ```bash
 # Create environment file
-cp backend/.env.example backend/.env
-# Edit backend/.env if needed (defaults work for local development)
+cp .env.example .env
+# Edit .env if needed (defaults work for local development)
 
 # Build with version from package.json
-./scripts/docker-build.sh
+./docker-build.sh
 
 # Start all services (nginx + backend + redis)
 docker compose up -d

scripts/docker-build.sh renamed to backend/docker-build.sh

@@ -1,7 +1,7 @@
 #!/bin/bash
 
 # Build Docker images with version from package.json
-VERSION=$(node -p "require('./package.json').version")
+VERSION=$(node -p "require('../package.json').version")
 export APP_VERSION=$VERSION
 
 echo "Building with version: $VERSION"

docker-compose.yml renamed to backend/docker-compose.yml

@@ -5,7 +5,7 @@ services:
       - "80:80"
     volumes:
       - ./nginx.conf:/etc/nginx/conf.d/default.conf
-      - ./out:/usr/share/nginx/html
+      - ../out:/usr/share/nginx/html
     depends_on:
       backend:
         condition: service_healthy
@@ -18,14 +18,14 @@ services:
 
   backend:
     build:
-      context: ./backend
+      context: .
       dockerfile: Dockerfile
       args:
         APP_VERSION: ${APP_VERSION:-0.15.0}
     ports:
       - "8000:8000"
     env_file:
-      - ./backend/.env
+      - .env
     environment:
       # Only override what needs Docker networking
       REDIS_URL: redis://redis:6379/0