Support both Unix epoch timestamps and RFC3339 format for build time injection via ldflags. Unix epoch format provides simpler build commands: $(date +%s) vs $(date -u +%Y-%m-%dT%H:%M:%SZ). - Add parseBuildTime() to convert epoch to RFC3339 - Maintain backward compatibility with existing RFC3339 format - Ensure consistent RFC3339 output regardless of input format - Fix build date priority over git commit time