feat: Prevent placing entities on water and improve land generation

ai.js

@@ -648,8 +648,21 @@ function deliverFruitTask(cit) {
 }
 
 function plantFruitTreeTask(cit) {
-  let px = cit.x + randInt(-50, 50);
-  let py = cit.y + randInt(-50, 50);
+  // Try to find a valid land position nearby
+  let px, py;
+  let attempts = 0;
+  do {
+    px = cit.x + randInt(-50, 50);
+    py = cit.y + randInt(-50, 50);
+    attempts++;
+    // Give up after too many attempts and find a new task
+    if (attempts > 20) {
+      cit.task = null;
+      cit.target = null;
+      return;
+    }
+  } while (!isValidPlacement(px, py));
+  
   moveToward(cit, px, py, 0.4);
   if(distance(cit.x, cit.y, px, py) < 10) {
     if(cit.carryingFruit >= FRUIT_PLANT_COST) {