feat(tictactoe): integrate leaderboard UI, provider API hook, and new styles

- Add *_BKP* ignore rule to .gitignore
- Insert Leaderboard component into TicTacToe screen
- Add getLeaderboardTop() API method to NakamaProvider and expose via context
- Add full leaderboard polling logic (interval-based) in new Leaderboard.tsx
- Style leaderboard in styles.css (rows, rank, name, score, empty state, card UI)
- Modernize TicTacToe UI styles (board, squares, buttons, layout)
- Replace matchmaking view with leaderboard integration
- Import ApiLeaderboardRecordList and ApiMatch types cleanly

src/tictactoe/styles.css

@@ -1,14 +1,16 @@
 body {
   font-family: sans-serif;
-  background: #f4f4f4;
+  background: #eaeef3;
   display: flex;
   justify-content: center;
   padding-top: 50px;
   margin: 0;
+  color: #222;
 }
 
 .game-container {
   text-align: center;
+  padding: 20px;
 }
 
 .board {
@@ -22,32 +24,111 @@ body {
 
 .square {
   background: white;
-  border: 2px solid #333;
-  font-size: 2rem;
+  border-radius: 10px;
+  border: 2px solid #444;
+  font-size: 2.2rem;
   font-weight: bold;
   cursor: pointer;
   height: 100px;
   width: 100px;
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  transition: 0.15s ease;
+  box-shadow: 0 2px 4px rgba(0,0,0,0.15);
 }
 
 .square:hover {
-  background: #eee;
+  background: #f1f1f1;
+  transform: scale(1.04);
 }
 
 .status {
-  font-size: 1.4rem;
-  margin-bottom: 10px;
+  font-size: 1.6rem;
+  margin-bottom: 15px;
+  font-weight: bold;
+  color: #222;
 }
 
 .reset-btn {
-  padding: 10px 20px;
-  background: #333;
+  padding: 12px 26px;
+  background: #3558d8;
   color: white;
   border: none;
   cursor: pointer;
   font-size: 1rem;
+  border-radius: 8px;
+  transition: 0.2s ease;
+  box-shadow: 0 2px 4px rgba(0,0,0,0.25);
 }
 
 .reset-btn:hover {
-  background: #555;
+  background: #2449c7;
+  transform: translateY(-2px);
 }
+
+.leaderboard {
+  width: 300px;
+  margin: 25px auto;
+  padding: 15px 20px;
+  background: white;
+  border-radius: 12px;
+  box-shadow: 0 2px 10px rgba(0,0,0,0.1);
+  font-family: sans-serif;
+}
+
+/* Leaderboard title */
+.leaderboard-title {
+  margin: 0 0 15px 0;
+  font-size: 1.4rem;
+  font-weight: 700;
+  text-align: center;
+  color: #222;
+}
+
+/* Each row */
+.leaderboard-row {
+  display: flex;
+  align-items: center;
+  padding: 10px 8px;
+  background: #f7f9fc;
+  border-radius: 8px;
+  margin-bottom: 8px;
+  box-shadow: 0 1px 2px rgba(0,0,0,0.08);
+}
+
+/* Empty state */
+.leaderboard-empty {
+  padding: 12px 0;
+  text-align: center;
+  color: #777;
+  font-size: 1rem;
+}
+
+/* Rank number */
+.leaderboard-rank {
+  width: 28px;
+  font-size: 1.2rem;
+  font-weight: 700;
+  color: #3558d8;
+}
+
+/* Username */
+.leaderboard-name {
+  flex: 1;
+  margin-left: 10px;
+  font-weight: 500;
+  color: #333;
+  white-space: nowrap;
+  overflow: hidden;
+  text-overflow: ellipsis;
+}
+
+/* Score value */
+.leaderboard-score {
+  width: 40px;
+  text-align: right;
+  font-weight: 700;
+  color: #111;
+}
+