feat(ui): weekend/vacation/checkbox colors follow accent theme

- Unify Saturday+Sunday into single isWeekend flag (header + grid lines)
- Replace hardcoded amber vacation bar/tooltip colors with brand-* classes
- Add global accent-color for checkboxes and radio buttons via CSS variable
- Update VACATION_TIMELINE_COLORS/BORDER to use brand palette (SICK stays red)
- Vacation-only tooltip uses neutral dark surface with brand accent border

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

apps/web/src/lib/status-styles.ts

@@ -49,17 +49,17 @@ export const ORDER_TYPE_BADGE: Record<string, string> = {
 
 /** Vacation overlay colors for timeline bars */
 export const VACATION_TIMELINE_COLORS: Record<string, string> = {
-  ANNUAL: "bg-orange-400/40",
+  ANNUAL: "bg-brand-400/40",
   SICK: "bg-red-500/40",
-  PUBLIC_HOLIDAY: "bg-violet-400/40",
-  OTHER: "bg-amber-400/40",
+  PUBLIC_HOLIDAY: "bg-brand-300/35",
+  OTHER: "bg-brand-400/30",
 };
 
 export const VACATION_TIMELINE_BORDER: Record<string, string> = {
-  ANNUAL: "border-orange-500",
+  ANNUAL: "border-brand-500",
   SICK: "border-red-600",
-  PUBLIC_HOLIDAY: "border-violet-500",
-  OTHER: "border-amber-500",
+  PUBLIC_HOLIDAY: "border-brand-400",
+  OTHER: "border-brand-500",
 };
 
 export const VACATION_TYPE_LABELS_SHORT: Record<string, string> = {