This commit addresses two primary issues in the backend Docker setup:
1. **Database Initialization Error (CGO_ENABLED):**
The Go binary was previously compiled with `CGO_ENABLED=0`. This caused an error ("Binary was compiled with 'CGO_ENABLED=0', go-sqlite3 requires cgo to work") because `go-sqlite3` requires CGo.
- Modified `Dockerfile.backend` to set `CGO_ENABLED=1` during the build.
- Added `gcc`, `musl-dev`, and `sqlite-dev` to the builder stage dependencies for CGo compilation on Alpine.
- Added `sqlite` to the final image stage for runtime library availability.
2. **fail2ban-client Not Found Error:**
The `DockerEntrypoint.sh` script attempted to start `fail2ban-client` without ensuring its presence in the image.
- Added `fail2ban` to the `apk add` command in the final stage of `Dockerfile.backend`.
- Updated `DockerEntrypoint.sh` to check if `fail2ban-client` is available before attempting to start it, preventing errors if it's not found (e.g., if `XUI_ENABLE_FAIL2BAN` is true but installation failed).
These changes should allow the backend container to build and start correctly, resolving the reported database and fail2ban errors. You will need to run `docker compose up -d --build` to apply these changes.
