Add game deletion with authorization check

- Add Delete method to GameStore and Persister interface
- Add delete button to game list on home page
- Verify user owns game before allowing deletion
- Use status constants instead of magic numbers
- Remove unused variable in persister

game/store.go

@@ -21,6 +21,7 @@ type Persister interface {
 	LoadGame(id string) (*Game, error)
 	SaveGamePlayer(gameID string, player *Player, slot int) error
 	LoadGamePlayers(gameID string) ([]*Player, error)
+	DeleteGame(id string) error
 }
 
 type GameStore struct {
@@ -99,6 +100,21 @@ func (gs *GameStore) Get(id string) (*GameInstance, bool) {
 	return gi, true
 }
 
+func (gs *GameStore) Delete(id string) error {
+	gs.gamesMu.Lock()
+	gi, ok := gs.games[id]
+	if ok {
+		delete(gs.games, id)
+		close(gi.done)
+	}
+	gs.gamesMu.Unlock()
+
+	if gs.persister != nil {
+		return gs.persister.DeleteGame(id)
+	}
+	return nil
+}
+
 func GenerateID(size int) string {
 	b := make([]byte, size)
 	rand.Read(b)