Add kubectl v1.31.4 to foxhunt-runtime Dockerfile so deploy step
doesn't need to download it each run. Deploy step falls back to
curl download if kubectl not found (for current image version).
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
detect-changes was falling back to Cargo.toml (rebuild-all) because jq
is not installed in foxhunt-runtime:latest. Replaced with grep+sed
extraction that needs no external dependencies. Also added jq to the
Dockerfile for future use.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>