feat: join pervious game added

src/app/pages/welcome/welcome.component.html

@@ -31,12 +31,44 @@
         <small>{{ creating ? 'Creating game...' : 'Start now' }}</small>
       </button>
 
-      <button type="button" class="mode mode-disabled" disabled>
-        <span>Future Technique</span>
-        <small>Placeholder</small>
+      <button type="button" class="mode mode-active" (click)="toggleJoinGameForm()" [disabled]="joiningGame">
+        <span>Join Game</span>
+        <small>{{ joiningGame ? 'Joining...' : 'Enter game ID' }}</small>
       </button>
     </div>
 
+    @if (showJoinGameForm) {
+      <div class="join-game-form">
+        <p>Enter the game ID:</p>
+        <div class="join-game-input-group">
+          <input
+            type="text"
+            class="join-game-input"
+            [(ngModel)]="gameIdInput"
+            placeholder="Paste game ID here"
+            [disabled]="joiningGame"
+            (keyup.enter)="joinGame()"
+          />
+          <button
+            type="button"
+            class="join-game-btn join"
+            (click)="joinGame()"
+            [disabled]="joiningGame || !gameIdInput.trim()"
+          >
+            {{ joiningGame ? 'Joining...' : 'Join' }}
+          </button>
+          <button
+            type="button"
+            class="join-game-btn cancel"
+            (click)="clearJoinGameForm()"
+            [disabled]="joiningGame"
+          >
+            Cancel
+          </button>
+        </div>
+      </div>
+    }
+
     @if (errorMessage) {
       <p class="error">{{ errorMessage }}</p>
     }