refactor: deduplicate modals, notifications, confirms, comboboxes, proficiency

Modal Overlay (Finding 1 — 6 admin files):
- Migrated CountriesClient, ManagementLevelsClient, OrgUnitsClient,
  CalculationRulesClient, UtilizationCategoriesClient, RoleModal
  from inline fixed-overlay to AnimatedModal component
- Gains: animated transitions, backdrop blur, escape key for free

Notification Helper (Finding 9 — 9 API files, 14 call sites):
- New createNotification() + createNotificationsForUsers() in
  packages/api/src/lib/create-notification.ts
- Handles exactOptionalPropertyTypes spread + SSE emit internally
- Simplified: budget-alerts, estimate-reminders, auto-staffing,
  vacation-conflicts, chargeability-alerts, comment, vacation, notification

ConfirmDialog (Finding 3 — 11 files):
- Replaced all window.confirm() calls with ConfirmDialog component
- Files: CommentThread, EffortRules, ExperienceMultipliers,
  ManagementLevels, CalculationRules, Countries, RateCards,
  ApplyEffortRules, ApplyExperienceMultipliers, NotificationCenter,
  ReminderModal

EntityCombobox (Finding 4 — 3 files):
- New generic EntityCombobox<T> with customization hooks
- ResourceCombobox + ProjectCombobox rewritten as thin wrappers
- All consumers unchanged (backwards-compatible props)

Proficiency Constants (Finding 2 — 2 files):
- SkillsAnalytics + SkillMarketplace now import from skills/shared.tsx
- Deleted ~70 LOC of local duplicate definitions

Regression: 283 engine + 37 staffing tests pass. TypeScript clean.
AI Assistant: all 87 tools verified accessible.

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

apps/web/src/components/notifications/ReminderModal.tsx

@@ -1,9 +1,10 @@
 "use client";
 
 import { useRef, useState } from "react";
+import { ConfirmDialog } from "~/components/ui/ConfirmDialog.js";
+import { DateInput } from "~/components/ui/DateInput.js";
 import { useFocusTrap } from "~/hooks/useFocusTrap.js";
 import { trpc } from "~/lib/trpc/client.js";
-import { DateInput } from "~/components/ui/DateInput.js";
 
 const RECURRENCE_OPTIONS = [
   { value: "", label: "None" },
@@ -50,6 +51,7 @@ export function ReminderModal({ reminder, onClose, onSuccess }: ReminderModalPro
   const [recurrence, setRecurrence] = useState(reminder?.recurrence ?? "");
   const [link, setLink] = useState(reminder?.link ?? "");
   const [serverError, setServerError] = useState<string | null>(null);
+  const [confirmDelete, setConfirmDelete] = useState(false);
 
   const panelRef = useRef<HTMLDivElement>(null);
   useFocusTrap(panelRef, true);
@@ -128,8 +130,7 @@ export function ReminderModal({ reminder, onClose, onSuccess }: ReminderModalPro
 
   function handleDelete() {
     if (!reminder) return;
-    if (!window.confirm("Delete this reminder?")) return;
-    deleteMutation.mutate({ id: reminder.id });
+    setConfirmDelete(true);
   }
 
   const inputClass =
@@ -303,6 +304,20 @@ export function ReminderModal({ reminder, onClose, onSuccess }: ReminderModalPro
           </div>
         </form>
       </div>
+
+      {confirmDelete && reminder && (
+        <ConfirmDialog
+          title="Delete reminder"
+          message="Are you sure you want to delete this reminder?"
+          confirmLabel="Delete"
+          variant="danger"
+          onConfirm={() => {
+            deleteMutation.mutate({ id: reminder.id });
+            setConfirmDelete(false);
+          }}
+          onCancel={() => setConfirmDelete(false)}
+        />
+      )}
     </div>
   );
 }