Migrate logging to go-mana-component; delete logging/ package

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

transport/config_test.go

@@ -2,7 +2,6 @@ package transport
 
 import (
 	"github.com/stretchr/testify/assert"
-	"log/slog"
 	"net/http"
 	"testing"
 	"time"
@@ -36,8 +35,6 @@ func TestDefaultConnectionConfig(t *testing.T) {
 		PingInterval:       20 * time.Second,
 		IncomingBufferSize: 100,
 		ErrorsBufferSize:   10,
-		LoggingEnabled:     true,
-		LogLevel:           nil,
 		Retry:              GetDefaultRetryConfig(),
 	})
 }
@@ -61,8 +58,6 @@ func TestApplyConnectionOptions(t *testing.T) {
 		conf,
 		WithIncomingBufferSize(256),
 		WithErrorsBufferSize(100),
-		WithLoggingEnabled(false),
-		WithLogLevel(slog.LevelError),
 		WithRetryMaxRetries(0),
 		WithRetryInitialDelay(3*time.Second),
 		WithRetryJitterFactor(0.5),
@@ -71,8 +66,6 @@ func TestApplyConnectionOptions(t *testing.T) {
 	assert.NoError(t, err)
 	assert.Equal(t, 256, conf.IncomingBufferSize)
 	assert.Equal(t, 100, conf.ErrorsBufferSize)
-	assert.False(t, conf.LoggingEnabled)
-	assert.Equal(t, slog.LevelError, *conf.LogLevel)
 	assert.Equal(t, 0, conf.Retry.MaxRetries)
 	assert.Equal(t, 3*time.Second, conf.Retry.InitialDelay)
 	assert.Equal(t, 0.5, conf.Retry.JitterFactor)