fix: sync log platform art collision alignment

src/main.js

@@ -7,6 +7,9 @@ const GROUND_Y = 628;
 const GROUND_SURFACE_Y = GROUND_Y - 4;
 const GROUND_ART_SCALE = 0.98;
 const GROUND_ART_SURFACE_OFFSET = 20;
+const LOG_FRAME_HEIGHT = 79;
+const LOG_ART_SURFACE_OFFSET = 17;
+const LOG_COLLIDER_HEIGHT = 16;
 
 class ForestScene extends Phaser.Scene {
   constructor() {
@@ -398,17 +401,23 @@ class ForestScene extends Phaser.Scene {
       [4680, 545], [4890, 505], [5100, 465]
     ];
 
-    branchPositions.forEach(([x, y], index) => {
+    // branchPositions store the intended walkable surface Y, not the
+    // collider centre. The illustrated log's usable top edge is 17 source
+    // pixels below its cropped frame top, so derive art + physics from the
+    // same surface coordinate.
+    branchPositions.forEach(([x, surfaceY], index) => {
       const scale = index % 3 === 0 ? 0.62 : 0.55;
-      const visual = this.add.image(x, y + 15, 'terrain-sheet', 'log-platform')
+      const visualY = surfaceY + ((LOG_FRAME_HEIGHT / 2 - LOG_ART_SURFACE_OFFSET) * scale);
+
+      const visual = this.add.image(x, visualY, 'terrain-sheet', 'log-platform')
         .setScale(scale)
         .setDepth(6);
 
       const collider = this.add.rectangle(
         x,
-        y,
+        surfaceY + (LOG_COLLIDER_HEIGHT / 2),
         Math.max(130, visual.displayWidth * 0.82),
-        16,
+        LOG_COLLIDER_HEIGHT,
         0x000000,
         0
       );