style(theme): update light mode color palette for softer tones and improved readability

src/styles/devcm-tokens.scss

@@ -42,11 +42,11 @@ html[data-color-scheme="dark"] {
 
 html[data-color-scheme="light"] {
   color-scheme: light;
-  --devcm-bg: #fdf6e3;
-  --devcm-bg-deep: #eee8d5;
-  --devcm-panel: rgba(253, 246, 227, 0.94);
-  --devcm-panel-soft: rgba(238, 232, 213, 0.78);
-  --devcm-panel-warm: rgba(238, 232, 213, 0.62);
+  --devcm-bg: #fdf8e8;
+  --devcm-bg-deep: #f4eedc;
+  --devcm-panel: rgba(255, 250, 235, 0.9);
+  --devcm-panel-soft: rgba(244, 238, 220, 0.5);
+  --devcm-panel-warm: rgba(244, 238, 220, 0.34);
   --devcm-line: rgba(101, 123, 131, 0.2);
   --devcm-line-strong: rgba(181, 137, 0, 0.42);
   --devcm-text: #586e75;