fix: resolve 3 concurrency issues in multi-table bot matches on Folia

- MahjongTableSession: make botTask volatile and synchronize
  setBotTask/clearBotTaskIfSame/cancelBotTask to prevent orphaned
  tasks when global-timer and region threads race on setBotTask
  (caused duplicate bot actions in multi-table scenarios).

- MahjongTableManager: move bot watchdog inside runRegion callback
  so game state (engine, currentPlayer, pendingReaction) is read from
  the owning region thread, not from the global timer thread.
  Also add try-catch around session.tick() which was previously
  swallowing dispatch failures.

- GameRoomManager: schedule forceEndTable on the table's region
  thread instead of calling it directly from tick() (global timer),
  preventing cross-thread mutation of round controller and viewer
  presentation state when player exit countdowns expire.

Fixes: bot matches freezing or duplicating actions when multiple
game rooms have tables running simultaneously.

Author: Arbousier1

src/main/java/top/ellan/mahjong/gameroom/GameRoomManager.java

@@ -338,7 +338,13 @@ public void tick() {
                 String tableId = this.exitCountdownTableIds.get(playerId);
                 if (tableId != null) {
                     this.logDebug("Player " + playerId + " countdown expired, force-ending table " + tableId);
-                    this.tableManager.forceEndTable(tableId);
+                    // Schedule force-end on the table's region thread to avoid
+                    // cross-thread mutation of game state (round controller,
+                    // viewer presentation, bot task, etc.) on Folia.
+                    MahjongTableSession session = this.tableManager.resolveTableById(tableId);
+                    if (session != null) {
+                        this.scheduler.runRegion(session.center(), () -> this.tableManager.forceEndTable(tableId));
+                    }
                 }
                 iterator.remove();
                 this.removeCountdownState(playerId);

src/main/java/top/ellan/mahjong/table/core/MahjongTableManager.java

@@ -735,27 +735,41 @@ private void dispatchTableTicks() {
         // other table on the server.
         for (MahjongTableSession session : this.directory.tables()) {
             try {
-                this.plugin.scheduler().runRegion(session.center(), session::tick);
+                this.plugin.scheduler().runRegion(session.center(), () -> this.tickSession(session));
             } catch (RuntimeException dispatchException) {
                 org.bukkit.Bukkit.getLogger().log(
                     java.util.logging.Level.WARNING,
                     "Failed to schedule tick for table " + session.id(),
                     dispatchException
                 );
             }
-            // Bot watchdog: if the session is started but has no armed bot task,
-            // the bot scheduler may have stalled (e.g. after an unhandled
-            // exception in a previous callback). Re-schedule to recover.
-            if (session.isStarted() && !session.hasArmedBotTask()) {
-                try {
-                    BotActionScheduler.schedule(session);
-                } catch (RuntimeException watchdogException) {
-                    org.bukkit.Bukkit.getLogger().log(
-                        java.util.logging.Level.WARNING,
-                        "Bot watchdog failed for table " + session.id(),
-                        watchdogException
-                    );
-                }
+        }
+    }
+
+    private void tickSession(MahjongTableSession session) {
+        try {
+            session.tick();
+        } catch (RuntimeException tickException) {
+            org.bukkit.Bukkit.getLogger().log(
+                java.util.logging.Level.WARNING,
+                "Tick failed for table " + session.id(),
+                tickException
+            );
+        }
+        // Bot watchdog: if the session is started but has no armed bot task,
+        // the bot scheduler may have stalled (e.g. after an unhandled
+        // exception in a previous callback). Re-schedule to recover.
+        // This runs on the region thread alongside tick() so that game state
+        // (engine, currentPlayer, etc.) is accessed from the owning thread.
+        if (session.isStarted() && !session.hasArmedBotTask()) {
+            try {
+                BotActionScheduler.schedule(session);
+            } catch (RuntimeException watchdogException) {
+                org.bukkit.Bukkit.getLogger().log(
+                    java.util.logging.Level.WARNING,
+                    "Bot watchdog failed for table " + session.id(),
+                    watchdogException
+                );
             }
         }
     }

src/main/java/top/ellan/mahjong/table/core/MahjongTableSession.java

@@ -85,7 +85,7 @@ public final class MahjongTableSession implements TableSessionMutator, TableMemb
     private PublicActionAnnouncement lastPublicActionAnnouncement;
     private PluginTask publicActionClearTask;
     private long publicActionAnnouncementSequence;
-    private PluginTask botTask;
+    private volatile PluginTask botTask;
     private final TableRenderCoordinator renderCoordinator;
     private final TableViewerPresentationCoordinator viewerPresentation;
     private final TableRegionDisplayCoordinator regionDisplayCoordinator;
@@ -1003,7 +1003,7 @@ public String gbSuggestedKanTile(UUID playerId) {
         return this.fromGbController(playerId, GbTableRoundController::suggestedBotKanTile, null);
     }
 
-    public void setBotTask(PluginTask botTask) {
+    public synchronized void setBotTask(PluginTask botTask) {
         PluginTask old = this.botTask;
         if (old != null && old != botTask) {
             old.cancel();
@@ -1016,7 +1016,7 @@ public void setBotTask(PluginTask botTask) {
      * task. This is used by bot callbacks to avoid clobbering a new task that
      * was set by the render cycle during execution.
      */
-    public void clearBotTaskIfSame(PluginTask expected) {
+    public synchronized void clearBotTaskIfSame(PluginTask expected) {
         if (this.botTask == expected) {
             this.botTask = null;
         }
@@ -1032,7 +1032,7 @@ public boolean hasArmedBotTask() {
         return current != null && !current.isCancelled();
     }
 
-    public void cancelBotTask() {
+    public synchronized void cancelBotTask() {
         if (this.botTask != null) {
             this.botTask.cancel();
             this.botTask = null;