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/components/timeline/DemandPopover.tsx

@@ -2,7 +2,7 @@
 
 import { useEffect, useRef } from "react";
 import type { TimelineDemandEntry } from "./TimelineContext.js";
-import { formatDateLong } from "~/lib/format.js";
+import { formatCents, formatDateLong } from "~/lib/format.js";
 
 interface DemandPopoverProps {
   demand: TimelineDemandEntry;
@@ -143,13 +143,13 @@ export function DemandPopover({
               <div>
                 <div className="text-gray-400 dark:text-gray-500 mb-0.5">Daily cost</div>
                 <div className="font-medium text-gray-800 dark:text-gray-200">
-                  {(demand.dailyCostCents / 100).toLocaleString("de-DE", { minimumFractionDigits: 2 })} EUR
+                  {formatCents(demand.dailyCostCents)} EUR
                 </div>
               </div>
               <div>
                 <div className="text-gray-400 dark:text-gray-500 mb-0.5">Total cost</div>
                 <div className="font-medium text-gray-800 dark:text-gray-200">
-                  {(budgetCents / 100).toLocaleString("de-DE", { minimumFractionDigits: 2 })} EUR
+                  {formatCents(budgetCents)} EUR
                 </div>
               </div>
             </>