- Restructure Dockerfile.alpine-musl for better layer caching
* Build dependencies (secp256k1, libwebsockets) in separate cached layers
* Copy submodules before source files to maximize cache hits
* Reduce rebuild time from ~2-3 minutes to ~10-15 seconds for source changes
- Remove 'musl' from binary names (c_relay_static_x86_64 instead of c_relay_static_musl_x86_64)
- Enforce static binary usage in make_and_restart_relay.sh
* Remove all fallbacks to regular make builds
* Exit with clear error if static binary not found
* Ensures JSON1 extension is always available
- Fix build_static.sh hanging on ldd check with timeout
- Remove sudo usage from build_static.sh (assumes docker group membership)
These changes ensure consistent builds with JSON1 support and dramatically improve
development iteration speed through intelligent Docker layer caching.