style(ui): tones down RepoGroupHeader visual weight

Reduces bg tint from info/20 to info/5 (hover info/10). Keeps oklch
repo-header-text but darkens dark-mode values (L 0.85→0.70, C 0.18→0.15)
for less visual competition with content rows.

Author: wgordon17

src/app/components/shared/RepoGroupHeader.tsx

@@ -15,7 +15,7 @@ interface RepoGroupHeaderProps {
 
 export default function RepoGroupHeader(props: RepoGroupHeaderProps) {
   return (
-    <div class={`group/repo-header flex items-center bg-info/20 border-y border-base-300 hover:bg-info/25 transition-colors duration-300 ${props.isHighlighted ? "animate-reorder-highlight" : ""}`}>
+    <div class={`group/repo-header flex items-center bg-info/5 border-y border-base-300 hover:bg-info/10 transition-colors duration-300 ${props.isHighlighted ? "animate-reorder-highlight" : ""}`}>
       <button
         onClick={() => props.onToggle()}
         aria-expanded={props.isExpanded}

src/app/index.css

@@ -55,7 +55,7 @@
 }
 
 @utility repo-header-text {
-  color: light-dark(oklch(0.45 0.15 250), oklch(0.85 0.18 250));
+  color: light-dark(oklch(0.45 0.15 250), oklch(0.70 0.15 250));
 }
 
 /* ── Notification animations ──────────────────────────────────────────────── */