[PHASE-6] Add logger helper

internal/lib/sl/sl.go

@@ -0,0 +1,27 @@
+package sl
+
+import (
+	"context"
+	"log/slog"
+)
+
+// Err creates a structured error attribute for slog
+func Err(err error) slog.Attr {
+	return slog.Attr{
+		Key:   "error",
+		Value: slog.StringValue(err.Error()),
+	}
+}
+
+// MockHandler is a test handler that discards all log messages
+type MockHandler struct{}
+
+func (h *MockHandler) Enabled(context.Context, slog.Level) bool  { return false }
+func (h *MockHandler) Handle(context.Context, slog.Record) error { return nil }
+func (h *MockHandler) WithAttrs([]slog.Attr) slog.Handler        { return h }
+func (h *MockHandler) WithGroup(string) slog.Handler             { return h }
+
+// NewMockLogger creates a logger that discards all messages for testing
+func NewMockLogger() *slog.Logger {
+	return slog.New(&MockHandler{})
+}