feat: confetti celebration tier rule and emoji set

- Fire confetti on 2nd bingo OR 1st bingo when another row is in Chờ
  (waiting for one number). Replaces old ≥3 threshold that rarely fired.
- Add Vietnamese hội-chợ emoji: 🥢 🎋 🏮 (chopsticks, bamboo, lantern)
- Per-particle size jitter (1.5–2.4x) for visual interest

Upstream: a60ea08

android/app/src/main/java/com/miti99/loto/state/PlayerBoardViewModel.kt

@@ -55,6 +55,7 @@ class PlayerBoardViewModel(
             grid = grid,
             crossed = crossed,
             rowComplete = List(grid.size) { false },
+            sectionHasWaiting = listOf(false, false, false),
         )
         persistDebounced()
     }
@@ -72,6 +73,7 @@ class PlayerBoardViewModel(
                 notifiedWaitingRows = emptySet(),
                 bingoEvent = null,
                 waitingToast = null,
+                sectionHasWaiting = listOf(false, false, false),
             )
         }
         persistDebounced()
@@ -108,6 +110,7 @@ class PlayerBoardViewModel(
             rowComplete = rowComplete,
             celebratedRows = celebrated,
             notifiedWaitingRows = notifiedWaiting,
+            sectionHasWaiting = computeSectionHasWaiting(gridArr, crossedArr, rowComplete),
         )
     }
 
@@ -163,7 +166,18 @@ class PlayerBoardViewModel(
                 if (i !in celebrated && rowComplete[i]) {
                     celebrated = celebrated + i
                     notifiedWaiting = notifiedWaiting + i
-                    val tier = if (celebrated.size >= 3) 2 else 1
+                    // Tier 2 confetti: 2nd bingo, OR 1st bingo while another row
+                    // is one cell from completion. Old "≥3 bingos" rule rarely
+                    // fired on a 9-row card so most wins felt under-celebrated.
+                    val hasActiveCho = grid.indices.any { otherRow ->
+                        otherRow !in celebrated &&
+                            GameLogic.getWaitingNumber(gridArr, crossedArr, otherRow) != null
+                    }
+                    val tier = when {
+                        celebrated.size >= 2 -> 2
+                        celebrated.size >= 1 && hasActiveCho -> 2
+                        else -> 1
+                    }
                     bingoEvent = BingoEvent(row1Based = i + 1, tier = tier)
                     if (announce) voicePlayer.playBingo()
                     return@run
@@ -193,6 +207,7 @@ class PlayerBoardViewModel(
                 bingoEvent = bingoEvent,
                 waitingToast = waitingToast,
                 lastConsumedEventId = lastConsumedEventId ?: it.lastConsumedEventId,
+                sectionHasWaiting = computeSectionHasWaiting(gridArr, crossedArr, rowComplete),
             )
         }
         persistDebounced()
@@ -241,4 +256,22 @@ class PlayerBoardViewModel(
 
     private fun toBoolArray(crossed: List<List<Boolean>>): Array<BooleanArray> =
         Array(crossed.size) { r -> BooleanArray(crossed[r].size) { c -> crossed[r][c] } }
+
+    /**
+     * Per-section waiting flag (rows 0-2, 3-5, 6-8). True when any row in
+     * the section has exactly 1 uncrossed number AND is not yet complete.
+     */
+    private fun computeSectionHasWaiting(
+        gridArr: Array<IntArray>,
+        crossedArr: Array<BooleanArray>,
+        rowComplete: List<Boolean>,
+    ): List<Boolean> {
+        val waitingRows = gridArr.indices.map { r ->
+            !rowComplete.getOrElse(r) { false } &&
+                GameLogic.getWaitingNumber(gridArr, crossedArr, r) != null
+        }
+        return listOf(0, 3, 6).map { start ->
+            (start until start + 3).any { r -> waitingRows.getOrElse(r) { false } }
+        }
+    }
 }

android/app/src/main/java/com/miti99/loto/ui/board/Confetti.kt

@@ -18,7 +18,9 @@ import androidx.compose.ui.platform.LocalConfiguration
 import androidx.compose.ui.unit.dp
 import androidx.compose.ui.unit.sp
 
-private val CONFETTI_EMOJI = listOf("🎊", "✨", "🎉", "🥳")
+// Hội-chợ flavour added (lantern, bamboo, chopsticks) so the celebration
+// set reads as Vietnamese fair, not generic party.
+private val CONFETTI_EMOJI = listOf("🎊", "✨", "🎉", "🥳", "🥢", "🎋", "🏮")
 private const val PARTICLE_COUNT = 12
 private const val DURATION_NS = 3_000_000_000L  // 3 seconds
 
@@ -28,6 +30,7 @@ private data class Particle(
     val speed: Float,             // px per second (screen height fraction)
     val rotationSpeed: Float,     // degrees per second
     val delayNs: Long,            // stagger start
+    val fontSizeSp: Float,        // per-piece size jitter
 )
 
 /**
@@ -49,12 +52,16 @@ fun Confetti(
 
     val particles = remember {
         List(PARTICLE_COUNT) { i ->
+            // Match upstream jitter range 1.5..2.4rem; render as sp.
+            // 1rem ≈ 16sp on default density.
+            val sizeRem = 1.5f + ((i * 13) % 11) / 10f
             Particle(
                 emoji = CONFETTI_EMOJI[i % CONFETTI_EMOJI.size],
                 startXFraction = (i.toFloat() / PARTICLE_COUNT) + (((i * 17) % 10) / 100f),
                 speed = screenHeightPx * (0.25f + (i % 5) * 0.05f),
                 rotationSpeed = 60f + (i % 7) * 30f,
                 delayNs = (i * 150_000_000L),  // 150 ms stagger
+                fontSizeSp = (sizeRem * 16f).coerceIn(24f, 38f),
             )
         }
     }
@@ -86,7 +93,7 @@ fun Confetti(
 
             Text(
                 text = p.emoji,
-                fontSize = 20.sp,
+                fontSize = p.fontSizeSp.sp,
                 modifier = Modifier
                     .offset(x = xDp.dp, y = yDp.dp)
                     .graphicsLayer { rotationZ = rotation % 360f },