What

• Replace Metal Agent fmt.Printf logging with structured zap logs in startup, runtime, and shutdown paths.
• Add --log-level parsing and production zap logger initialization in cmd/metal-agent/main.go.
• Inject a shared sugared logger into agent subsystems (watcher, executor, registry) with no-op fallbacks for optional constructor usage.
• Add contextual fields (component, subsystem, namespace/name/port/pid/error) to improve observability and troubleshooting.

Why

Metal agent logs were previously plain text and inconsistent across components. This change standardizes logging, enables configurable verbosity, and improves operational debugging with structured context.

How

• Introduced a production zap logger in cmd/metal-agent/main.go via a small newLogger(level) helper.
• Added parseLogLevel to map --log-level (debug|info|warn|error) into zapcore levels, defaulting to info.
• Replaced user-facing fmt.Printf startup/runtime/shutdown logs with structured SugaredLogger calls (Infow, Warnw, Errorw, Debugw) and contextual fields.
• Extended MetalAgentConfig to accept an injected logger and propagated scoped child loggers into watcher, executor, and registry (component/subsystem fields).
• Kept constructors backward-compatible by allowing optional logger injection with a zap.NewNop().Sugar() fallback when none is provided.
• Added a TODO in cmd/metal-agent/main.go to wire this logger into controller-runtime (ctrl.SetLogger) so controller-runtime/client logs use the same config.

Checklist

• Tests added/updated
• make test passes locally
• make lint passes locally
• Commit messages follow conventional commits
• All commits are signed off (git commit -s) per DCO
• Documentation updated (if user-facing change)