chore: release v0.20.15 — colour redesign + nav-badge visibility fix

Bundles the Indigo accent migration, module-colour decoupling, WCAG
contrast improvements and nav-badge base-style relocation into one
release. See CHANGELOG.md [0.20.15] for full details.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

public/styles/dashboard.css

@@ -1040,8 +1040,8 @@
   width: 32px;
   height: 32px;
   border-radius: var(--radius-full);
-  background: rgba(255 255 255 / 0.18);
-  border: 1px solid rgba(255 255 255 / 0.3);
+  background: var(--color-glass);
+  border: 1px solid var(--color-glass-hover);
   color: var(--color-text-on-accent);
   cursor: pointer;
   flex-shrink: 0;
@@ -1050,8 +1050,8 @@
 
 .widget-customize-btn:hover,
 .widget-customize-btn:focus-visible {
-  background: rgba(255 255 255 / 0.3);
-  outline: 2px solid rgba(255 255 255 / 0.5);
+  background: var(--color-glass-hover);
+  outline: 2px solid rgba(255, 255, 255, 0.5);
   outline-offset: 2px;
 }