feat: strengthen dock spring motion, directional follow and milky glass

mobile/test/widgets/glass_material_test.dart

@@ -23,8 +23,8 @@ void main() {
       // while its original cool colour remains visible through the material.
       final red = _channel(pixels, 160, 43, 0);
       final green = _channel(pixels, 160, 43, 1);
-      expect(red, greaterThan(45));
-      expect(red, lessThan(90));
+      expect(red, greaterThan(75));
+      expect(red, lessThan(115));
       expect(green - red, closeTo(13, 6));
     },
   );
@@ -85,11 +85,10 @@ void main() {
       final red = _channel(pixels, 16, 40, 0);
       final green = _channel(pixels, 16, 40, 1);
       final blue = _channel(pixels, 16, 40, 2);
-      expect(red, lessThan(115));
-      expect(green - red, greaterThanOrEqualTo(80));
-      // The milky base and resting grey lens still transmit over half of the
-      // cyan source's 210-level blue/red contrast rather than becoming opaque.
-      expect(blue - red, greaterThan(105));
+      expect(red, lessThan(125));
+      expect(green - red, greaterThanOrEqualTo(65));
+      // The thicker milky base still transmits a clear cyan colour difference.
+      expect(blue - red, greaterThan(90));
     },
   );
 
@@ -133,8 +132,8 @@ void main() {
             reds.reduce((a, b) => a > b ? a : b) -
             reds.reduce((a, b) => a < b ? a : b);
         // The original stripes have 180 levels of contrast. Both the base and
-        // selected lens retain over half, keeping these larger shapes readable.
-        expect(contrast, greaterThan(90), reason: 'background at x=$start');
+        // selected lens retain at least 40%, keeping larger shapes readable.
+        expect(contrast, greaterThan(72), reason: 'background at x=$start');
       }
     },
   );