feat(slog): add slog.Handler adapter for log-socket

Implements log/slog.Handler that routes structured log records into the
log-socket broadcasting system. Supports namespaces, WithAttrs,
WithGroup, and configurable minimum level.

Also adds Broadcast() as a public entry point for adapter packages
that construct log.Entry values directly.

slog/handler_test.go

@@ -0,0 +1,118 @@
+package slog
+
+import (
+	"context"
+	"log/slog"
+	"testing"
+	"time"
+
+	"github.com/taigrr/log-socket/v2/log"
+)
+
+// getWithTimeout reads from a log client with a timeout to avoid hanging tests.
+func getWithTimeout(c *log.Client, timeout time.Duration) (log.Entry, bool) {
+	ch := make(chan log.Entry, 1)
+	go func() { ch <- c.Get() }()
+	select {
+	case e := <-ch:
+		return e, true
+	case <-time.After(timeout):
+		return log.Entry{}, false
+	}
+}
+
+func TestHandler_Enabled(t *testing.T) {
+	h := NewHandler(WithLevel(slog.LevelWarn))
+	if h.Enabled(context.Background(), slog.LevelInfo) {
+		t.Error("expected Info to be disabled when min level is Warn")
+	}
+	if !h.Enabled(context.Background(), slog.LevelWarn) {
+		t.Error("expected Warn to be enabled")
+	}
+	if !h.Enabled(context.Background(), slog.LevelError) {
+		t.Error("expected Error to be enabled")
+	}
+}
+
+func TestHandler_Handle(t *testing.T) {
+	c := log.CreateClient()
+	defer c.Destroy()
+	c.SetLogLevel(log.LTrace)
+
+	h := NewHandler(WithNamespace("test-ns"))
+	logger := slog.New(h)
+
+	logger.Info("hello world", "key", "value")
+
+	e, ok := getWithTimeout(c, time.Second)
+	if !ok {
+		t.Fatal("timed out waiting for log entry")
+	}
+	if e.Namespace != "test-ns" {
+		t.Errorf("namespace = %q, want %q", e.Namespace, "test-ns")
+	}
+	if e.Level != "INFO" {
+		t.Errorf("level = %q, want INFO", e.Level)
+	}
+	if e.Output == "" {
+		t.Error("output should not be empty")
+	}
+}
+
+func TestHandler_WithAttrs(t *testing.T) {
+	c := log.CreateClient()
+	defer c.Destroy()
+	c.SetLogLevel(log.LTrace)
+
+	h := NewHandler()
+	h2 := h.WithAttrs([]slog.Attr{slog.String("service", "api")})
+	logger := slog.New(h2)
+
+	logger.Info("request")
+
+	e, ok := getWithTimeout(c, time.Second)
+	if !ok {
+		t.Fatal("timed out")
+	}
+	if e.Output != "request service=api" {
+		t.Errorf("output = %q, want %q", e.Output, "request service=api")
+	}
+}
+
+func TestHandler_WithGroup(t *testing.T) {
+	c := log.CreateClient()
+	defer c.Destroy()
+	c.SetLogLevel(log.LTrace)
+
+	h := NewHandler()
+	h2 := h.WithGroup("http").WithAttrs([]slog.Attr{slog.Int("status", 200)})
+	logger := slog.New(h2)
+
+	logger.Info("done")
+
+	e, ok := getWithTimeout(c, time.Second)
+	if !ok {
+		t.Fatal("timed out")
+	}
+	if e.Output != "done http.status=200" {
+		t.Errorf("output = %q, want %q", e.Output, "done http.status=200")
+	}
+}
+
+func TestSlogLevelMapping(t *testing.T) {
+	tests := []struct {
+		level slog.Level
+		want  string
+	}{
+		{slog.LevelDebug, "DEBUG"},
+		{slog.LevelInfo, "INFO"},
+		{slog.LevelWarn, "WARN"},
+		{slog.LevelError, "ERROR"},
+	}
+	for _, tt := range tests {
+		got := slogLevelToString(tt.level)
+		if got != tt.want {
+			t.Errorf("slogLevelToString(%v) = %q, want %q", tt.level, got, tt.want)
+		}
+	}
+}