* fix: remove vmlinux crate dep
* fix: download architecture-specific vmlinux.h at build time
Instead of using a git dependency (not allowed on crates.io), download the
architecture-specific vmlinux.h header at build time from the libbpf/vmlinux.h
repository. This approach:
- Removes git dependency from Cargo.toml (crates.io compatible)
- Downloads correct arch-specific header (x86, aarch64, arm)
- Caches downloaded headers in OUT_DIR (reuses between builds)
- Works with cargo install
- Supports cross-compilation for all architectures
The vmlinux.h file (~3-4MB per arch) is downloaded once per architecture
and cached, so subsequent builds are fast.
* fix: use ureq with rustls instead of http_req
http_req depends on native-tls/openssl-sys which requires OpenSSL to be
installed in the cross-compilation containers. Switch to ureq with the
rustls backend which has no system dependencies and works in all
cross-compilation environments.
* fix: follow symlink when downloading vmlinux.h
The vmlinux.h files in the libbpf/vmlinux.h repository are symlinks to
versioned files (e.g. vmlinux_6.14.h). When downloading via
raw.githubusercontent.com, we get the symlink content (just the target
filename) instead of the actual file.
Solution: Download the symlink first to get the target filename, then
download the actual versioned file. This ensures we get the full header
content instead of just the symlink text.
* add crate publish workflow
