feat: rebrand AgendaPro -> AgendaMax + calendar fixes + current-week demo seed

- Rebrand all user-facing text to AgendaMax
- Fix sidebar scrolling: card container no longer overflows html (flex h-full min-h-0)
- Fix calendar toolbar hover: active buttons keep readable contrast
- Sticky calendar toolbar (month/week/day always visible on scroll)
- Seed guarantees 2-4 appointments per day for current week (Mon-Sat)

server/lib/metrics.ts

@@ -0,0 +1,20 @@
+// server/lib/metrics.ts
+// Pure KPI metric definitions. All return 0 when there is no data (no divide-by-zero).
+
+/** Cancellation rate: cancelled / total, rounded to 1 decimal (percent). */
+export function cancelRate(cancelled: number, total: number): number {
+  if (total <= 0) return 0;
+  return Math.round((cancelled / total) * 1000) / 10;
+}
+
+/** No-show rate: noShow / total, rounded to 1 decimal (percent). */
+export function noShowRate(noShow: number, total: number): number {
+  if (total <= 0) return 0;
+  return Math.round((noShow / total) * 1000) / 10;
+}
+
+/** Completion rate: completed / total, rounded to the nearest whole percent. */
+export function completionRate(completed: number, total: number): number {
+  if (total <= 0) return 0;
+  return Math.round((completed / total) * 100);
+}