Replaces the flat key-value logging scheme with component-based structured
logging via go-mana-component. Each layer (pool, worker, connection) builds
its own component identity and derives a *slog.Logger from a caller-supplied
slog.Handler.
- Delete logging/ package (logging.go, logging_test.go)
- Strip LoggingEnabled and LogLevel from ConnectionConfig, PoolConfig,
WorkerConfig; remove associated option funcs
- Change NewConnection and NewConnectionFromSocket to accept ctx and
slog.Handler instead of *slog.Logger; constructors build component
identity via MustNew/MustExtend internally
- Change WorkerFactory, NewWorker, connect, and RunDialer to carry
slog.Handler; remove PoolPlugin.Handler
- Change NewPool to establish pool component identity via MustNew;
remove pool_id field, PoolPlugin.ID, and ErrInvalidPoolID
- Fix data race in MockSlogHandler: WithAttrs now shares parent mutex
pointer rather than allocating a new one per child
- Run go fix
Jay