fix(docker): allow build scripts to dlopen libclang in Alpine musl

In Alpine, Rust build scripts are compiled for the musl host target which
defaults to static linking. Static musl binaries cannot dlopen, causing
bindgen to fail when loading libclang.so for z3 FFI generation.

Set CARGO_HOST_RUSTFLAGS="-C target-feature=-crt-static" so build scripts
are dynamically linked (can dlopen) while the target CLI binary stays static.

Author: drew

deploy/docker/Dockerfile.cli-musl

@@ -17,6 +17,11 @@ ARG CARGO_TARGET_CACHE_SCOPE=default
 
 ENV PATH="/usr/local/cargo/bin:${PATH}"
 ENV LIBCLANG_PATH="/usr/lib"
+# Build scripts (build.rs) are compiled for the host, which in Alpine defaults
+# to static musl linking.  Static musl binaries cannot dlopen, so bindgen fails
+# to load libclang.so.  Disabling crt-static for host builds makes build scripts
+# dynamically linked while keeping the target CLI binary fully static.
+ENV CARGO_HOST_RUSTFLAGS="-C target-feature=-crt-static"
 
 WORKDIR /build