feat: game session, turn system, lobby, and room events

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

game/session_test.go

@@ -0,0 +1,29 @@
+package game
+
+import (
+	"testing"
+	"time"
+
+	"github.com/tolelom/catacombs/entity"
+)
+
+func TestSessionTurnTimeout(t *testing.T) {
+	s := NewGameSession()
+	p := entity.NewPlayer("test", entity.ClassWarrior)
+	s.AddPlayer(p)
+	s.StartFloor()
+
+	// Don't submit any action, wait for timeout
+	done := make(chan struct{})
+	go func() {
+		s.RunTurn()
+		close(done)
+	}()
+
+	select {
+	case <-done:
+		// Turn completed via timeout
+	case <-time.After(7 * time.Second):
+		t.Error("Turn did not timeout within 7 seconds")
+	}
+}