v1.2.0: Implement improvement plan features

- Setback System: Teleports flagged players to lastSafeLocation (opt-in per check)
- TPS Lag Compensation: isServerLagging() helper, guards in Fly/Spider/Glide checks
- Universal Buffer System: Buffer fields for Jesus/Reach/KillAura/Timer/FastPlace/Scaffold/FastEat
- /xac debug command: Shows check-specific debug info for players
- Public API: XACApi with isFlagged(), getViolationLevel(), getTotalViolations(), isBypassed()
- Performance Metrics: /xac stats command with checks/flags/punishments tracking

src/main/java/com/xeroth/xeroanticheat/check/Check.java

@@ -2,6 +2,7 @@ package com.xeroth.xeroanticheat.check;
 
 import com.xeroth.xeroanticheat.XeroAntiCheat;
 import com.xeroth.xeroanticheat.data.PlayerData;
+import org.bukkit.Bukkit;
 import org.bukkit.entity.Player;
 
 /**
@@ -125,4 +126,19 @@ public abstract class Check {
             || player.hasPermission("xac.bypass." + getCategory())
             || player.hasPermission("xac.bypass." + name.toLowerCase());
     }
+    
+    protected void setback(Player player, PlayerData data) {
+        if (!getConfigBoolean("setback", false)) return;
+        org.bukkit.Location safe = data.getLastSafeLocation();
+        if (safe == null) return;
+        data.clearPositionHistory();
+        player.teleport(safe);
+    }
+    
+    protected boolean isServerLagging() {
+        if (!plugin.getConfigManager().getBoolean("tps.enabled", true)) return false;
+        double tps = Bukkit.getTPS()[0];
+        double minTps = plugin.getConfigManager().getDouble("tps.min_tps_threshold", 18.0);
+        return tps < minTps;
+    }
 }