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>

packages/api/src/router/assistant-tools.ts

@@ -9,6 +9,7 @@ import type { PermissionKey } from "@planarchy/shared";
 import { parseTaskAction } from "@planarchy/shared";
 import { createDalleClient, isDalleConfigured, parseAiError } from "../ai-client.js";
 import { getTaskAction } from "../lib/task-actions.js";
+import { fmtEur } from "../lib/format-utils.js";
 import { resolveRecipients } from "../lib/notification-targeting.js";
 import {
   emitNotificationCreated,
@@ -41,10 +42,6 @@ type ToolExecutor = (params: any, ctx: ToolContext) => Promise<unknown>;
 
 // ─── Helpers ────────────────────────────────────────────────────────────────
 
-function fmtEur(cents: number): string {
-  return `${(cents / 100).toLocaleString("de-DE", { minimumFractionDigits: 2 })} EUR`;
-}
-
 function fmtDate(d: Date | null | undefined): string | null {
   return d ? d.toISOString().slice(0, 10) : null;
 }