fix(ui): remove utilization row background tint from timeline

Remove the colored background tint for 50-100% utilized rows entirely.
Only over-utilized rows (>100%) keep the red warning tint.

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

apps/web/src/components/timeline/TimelineResourcePanel.tsx

@@ -411,13 +411,11 @@ function TimelineResourcePanelInner({
           ? ROW_HEIGHT
           : Math.max(ROW_HEIGHT, laneCount * SUB_LANE_HEIGHT + 16);
 
-        // Utilization background tint
+        // Utilization background tint — only highlight over-utilization
         const utilPct = utilizationByResource.get(resource.id) ?? 0;
         const utilBg = utilPct > 100
           ? "rgba(254,202,202,0.18)" // red tint for over-utilized
-          : utilPct >= 50
-            ? `rgba(34,197,94,${Math.min(0.04 + (utilPct - 50) * 0.001, 0.08)})` // faint green tint scaling 50-100%
-            : undefined;
+          : undefined;
 
         return (
           <div