feat: production deployment setup and hardcoded URL fixes

- Fix hardcoded localhost:8000 URLs in frontend to use relative /api/v1
  path (works with Nginx proxy in prod and VITE_API_URL in dev)
- Create production entrypoint (entrypoint.prod.sh) that runs migrations,
  seeds, and starts uvicorn with 4 workers (no --reload)
- Create comprehensive install.sh script for production deployment that
  generates secure .env, builds containers, waits for health, and
  optionally triggers initial MITRE sync
- Update docker-compose.prod.yml to use production entrypoint
- Update Dockerfile to make both entrypoints executable
- Remove init.ps1 (production will always be Linux)
- Update README with production deployment instructions

backend/Dockerfile

@@ -16,8 +16,8 @@ RUN pip install --no-cache-dir -r requirements.txt
 # Copy application code
 COPY . .
 
-# Make entrypoint executable
-RUN chmod +x /app/entrypoint.sh
+# Make entrypoints executable
+RUN chmod +x /app/entrypoint.sh /app/entrypoint.prod.sh
 
 # Expose port
 EXPOSE 8000