refactor: consolidate duplicated code across web and API packages

- Extract shared render helpers (vacation blocks, range overlay, overbooking blink) into renderHelpers.tsx
- Centralize status badge styles and vacation color maps into status-styles.ts
- Extract dragMath.ts utility from useTimelineDrag for reuse
- Split useInvalidatePlanningViews into useInvalidateTimeline (4 queries) + useInvalidatePlanningViews (8 queries)
- Adopt findUniqueOrThrow() and Prisma select constants across API routers
- Add shared fmtEur() helper for API-side money formatting
- Wrap TimelineResourcePanel and TimelineProjectPanel with React.memo
- Fix pre-existing TS2589 deep type errors in TeamCalendar and VacationModal
- 38 files changed, reducing ~400 lines of duplicated code

Co-Authored-By: claude-flow <ruv@ruv.net>

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

@@ -46,3 +46,33 @@ export const ORDER_TYPE_BADGE: Record<string, string> = {
   INTERNAL: "bg-blue-100 text-blue-700",
   OVERHEAD: "bg-gray-100 text-gray-700",
 };
+
+/** Vacation overlay colors for timeline bars */
+export const VACATION_TIMELINE_COLORS: Record<string, string> = {
+  ANNUAL: "bg-orange-400/40",
+  SICK: "bg-red-500/40",
+  PUBLIC_HOLIDAY: "bg-violet-400/40",
+  OTHER: "bg-amber-400/40",
+};
+
+export const VACATION_TIMELINE_BORDER: Record<string, string> = {
+  ANNUAL: "border-orange-500",
+  SICK: "border-red-600",
+  PUBLIC_HOLIDAY: "border-violet-500",
+  OTHER: "border-amber-500",
+};
+
+export const VACATION_TYPE_LABELS_SHORT: Record<string, string> = {
+  ANNUAL: "Annual",
+  SICK: "Sick",
+  PUBLIC_HOLIDAY: "Holiday",
+  OTHER: "Other",
+};
+
+/** Vacation calendar dot/bar colors */
+export const VACATION_CALENDAR_COLORS: Record<string, string> = {
+  ANNUAL: "bg-brand-500",
+  SICK: "bg-red-400",
+  PUBLIC_HOLIDAY: "bg-emerald-500",
+  OTHER: "bg-purple-400",
+};