fix: use browser-measured slot positions for Ludo base pieces

Measured actual slot center coordinates from the rendered DOM instead
of calculating from CSS math. Fixes piece-to-slot misalignment.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

public/js/ludo-constants.js

@@ -106,29 +106,29 @@ var LudoConstants = (function() {
     404: [9, 7],
     405: [8, 7],
 
-    // P1 Base positions (bottom-left quadrant, cols 0-5, rows 9-14)
-    500: [1.64, 10.64],
-    501: [3.36, 10.64],
-    502: [1.64, 12.36],
-    503: [3.36, 12.36],
-
-    // P2 Base positions (top-left quadrant, cols 0-5, rows 0-5)
-    600: [1.64, 1.64],
-    601: [3.36, 1.64],
-    602: [1.64, 3.36],
-    603: [3.36, 3.36],
-
-    // P3 Base positions (top-right quadrant, cols 9-14, rows 0-5)
-    700: [10.64, 1.64],
-    701: [12.36, 1.64],
-    702: [10.64, 3.36],
-    703: [12.36, 3.36],
-
-    // P4 Base positions (bottom-right quadrant, cols 9-14, rows 9-14)
-    800: [10.64, 10.64],
-    801: [12.36, 10.64],
-    802: [10.64, 12.36],
-    803: [12.36, 12.36]
+    // P1 Base positions (measured from browser)
+    500: [1.83, 10.84],
+    501: [3.18, 10.84],
+    502: [1.83, 12.18],
+    503: [3.18, 12.18],
+
+    // P2 Base positions (measured from browser)
+    600: [1.83, 1.83],
+    601: [3.18, 1.83],
+    602: [1.83, 3.18],
+    603: [3.18, 3.18],
+
+    // P3 Base positions (measured from browser)
+    700: [10.84, 1.83],
+    701: [12.18, 1.83],
+    702: [10.84, 3.18],
+    703: [12.18, 3.18],
+
+    // P4 Base positions (measured from browser)
+    800: [10.84, 10.84],
+    801: [12.18, 10.84],
+    802: [10.84, 12.18],
+    803: [12.18, 12.18]
   };
 
   var BASE_POSITIONS = {