fix(games): add 'Join the game' escape to WaitingForPartner screen (B-004)

The generic WaitingForPartner screen only exited when the session became null, so a partner who
landed there for an async game they could actually play (every current game is async — both play
on their own device) was stuck waiting forever, recoverable only via Back to Games. Now the screen
resolves the active session's game route and offers a primary 'Join the game' action that drops the
user into the game (which auto-joins the session). Deterministic repro: QA starts How Well, Sam
opens a different game -> one-game lock routes Sam to WaitingForPartner -> 'Join the game' -> How
Well guess intro. Verified live.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

app/src/main/java/app/closer/ui/games/WaitingForPartnerScreen.kt

@@ -47,7 +47,13 @@ data class WaitingForPartnerUiState(
     val isLoading: Boolean = true,
     val gameType: String = GameType.WHEEL,
     val partnerName: String = "Partner",
-    val navigateTo: String? = null
+    val navigateTo: String? = null,
+    /**
+     * Route into the partner's active game so this user can play their part, instead of being
+     * stuck on this "waiting" screen. Every current game is async (both play on their own device),
+     * so the partner who lands here can always join. Null only for an unknown game type. B-004.
+     */
+    val joinRoute: String? = null
 )
 
 @HiltViewModel
@@ -81,7 +87,8 @@ class WaitingForPartnerViewModel @Inject constructor(
                         it.copy(
                             isLoading = false,
                             gameType = session.gameType,
-                            partnerName = partnerName
+                            partnerName = partnerName,
+                            joinRoute = gameTypeRoute(session.gameType)
                         )
                     }
                 }
@@ -173,11 +180,30 @@ fun WaitingForPartnerScreen(
                         style = MaterialTheme.typography.bodySmall
                     )
 
-                    Button(
+                    // Primary action: join the partner's game and play your part. Without this the
-                        onClick = { onNavigate(AppRoute.PLAY) },
+                    // screen was a dead-end for async games the user could actually play (B-004).
-                        modifier = Modifier.fillMaxWidth()
+                    state.joinRoute?.let { route ->
-                    ) {
+                        Button(
-                        Text("Back to Games")
+                            onClick = { onNavigate(route) },
+                            modifier = Modifier.fillMaxWidth()
+                        ) {
+                            Text("Join the game")
+                        }
+                    }
+                    if (state.joinRoute != null) {
+                        TextButton(
+                            onClick = { onNavigate(AppRoute.PLAY) },
+                            modifier = Modifier.fillMaxWidth()
+                        ) {
+                            Text("Back to Games")
+                        }
+                    } else {
+                        Button(
+                            onClick = { onNavigate(AppRoute.PLAY) },
+                            modifier = Modifier.fillMaxWidth()
+                        ) {
+                            Text("Back to Games")
+                        }
                     }
                     TextButton(onClick = viewModel::abandonPartnerGame) {
                         Text(
@@ -200,6 +226,15 @@ private fun gameTypeLabel(gameType: String): String = when (gameType) {
     else -> gameType
 }
 
+/** Entry route that joins the partner's active game (each game screen auto-joins on open). B-004. */
+private fun gameTypeRoute(gameType: String): String? = when (gameType) {
+    GameType.WHEEL -> AppRoute.SPIN_WHEEL_RANDOM
+    GameType.THIS_OR_THAT -> AppRoute.THIS_OR_THAT
+    GameType.HOW_WELL -> AppRoute.HOW_WELL
+    GameType.DESIRE_SYNC -> AppRoute.DESIRE_SYNC
+    else -> null
+}
+
 private fun gameTypeGlyphKey(gameType: String): String = when (gameType) {
     GameType.WHEEL -> "play"
     GameType.THIS_OR_THAT -> "question"