feat: add custom CA certificate support

- Add support for custom CA certificates in Docker setup
- Two mounting options: individual certs or system CA bundle
- Automatic detection and configuration via NODE_EXTRA_CA_CERTS
- Enhanced documentation with setup guide in certs/README.md
- Added ca-certificates package to Alpine base image
- Updated docker-compose with clear volume mount examples
- Bump version to 2.21.0

docker-compose.dev.yml

@@ -54,6 +54,11 @@ services:
       - "4321:4321"
     volumes:
       - gitea-mirror-data:/app/data
+      # Mount custom CA certificates - choose one option:
+      # Option 1: Mount individual CA certificates from certs directory
+      # - ./certs:/app/certs:ro
+      # Option 2: Mount system CA bundle (if your CA is already in system store)
+      # - /etc/ssl/certs/ca-certificates.crt:/etc/ssl/certs/ca-certificates.crt:ro
     depends_on:
       - gitea
     environment:
@@ -80,6 +85,8 @@ services:
       - GITEA_ORGANIZATION=${GITEA_ORGANIZATION:-github-mirrors}
       - GITEA_ORG_VISIBILITY=${GITEA_ORG_VISIBILITY:-public}
       - DELAY=${DELAY:-3600}
+      # Optional: Skip TLS verification (insecure, use only for testing)
+      # - GITEA_SKIP_TLS_VERIFY=${GITEA_SKIP_TLS_VERIFY:-false}
     healthcheck:
       test: ["CMD", "wget", "--no-verbose", "--tries=1", "--spider", "http://localhost:4321/api/health"]
       interval: 30s