Replace timestamp-based and 'latest' defaults with git rev-parse --short
HEAD across build.js, deploy.js, and push.js for consistent, traceable
image tags tied to source commits.
- build.js: cargo build first, then docker build — no more Docker-in-Docker
- .dockerignore: exclude target/ but re-include
target/x86_64-unknown-linux-gnu/release/ so pre-built binaries
are available in Docker build context
- Strip builder stage from all Rust Dockerfiles; images now only contain
the runtime and a pre-built binary copied from target/.
- build.js: cargo builds all Rust binaries first (using all CPU cores),
then copies them into Docker images.
- .drone.yml: add cargo-build step before docker-build so kaniko can COPY
the pre-compiled binaries without rebuilding inside the image.
