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/admin/CalculationRulesClient.tsx

@@ -1,6 +1,8 @@
 "use client";
 
 import { useState } from "react";
+import { AnimatedModal } from "~/components/ui/AnimatedModal.js";
+import { ConfirmDialog } from "~/components/ui/ConfirmDialog.js";
 import { InfoTooltip } from "~/components/ui/InfoTooltip.js";
 import { trpc } from "~/lib/trpc/client.js";
 
@@ -71,6 +73,7 @@ const emptyRule: EditingRule = {
 
 export function CalculationRulesClient() {
   const [editing, setEditing] = useState<EditingRule | null>(null);
+  const [confirmDeleteRule, setConfirmDeleteRule] = useState<string | null>(null);
   const [error, setError] = useState<string | null>(null);
 
   const utils = trpc.useUtils();
@@ -219,7 +222,7 @@ export function CalculationRulesClient() {
                   <td className="px-4 py-3 text-right text-sm">
                     <button onClick={() => openEdit(rule)} className="mr-2 text-blue-600 hover:underline dark:text-blue-400">Edit</button>
                     <button
-                      onClick={() => { if (confirm("Delete this rule?")) deleteMut.mutate({ id: rule.id }); }}
+                      onClick={() => setConfirmDeleteRule(rule.id)}
                       className="text-red-600 hover:underline dark:text-red-400"
                     >
                       Delete
@@ -240,9 +243,9 @@ export function CalculationRulesClient() {
       </div>
 
       {/* ── Edit/Create Modal ── */}
-      {editing && (
-        <div className="fixed inset-0 z-50 flex items-center justify-center bg-black/50">
-          <div className="w-full max-w-lg rounded-lg bg-white p-6 shadow-xl dark:bg-gray-800">
+      <AnimatedModal open={editing !== null} onClose={() => setEditing(null)} maxWidth="max-w-lg">
+        {editing && (<>
+            <div className="p-6">
             <h2 className="mb-4 text-lg font-semibold text-gray-900 dark:text-gray-100">
               {editing.id ? "Edit Rule" : "New Rule"}
             </h2>
@@ -363,8 +366,22 @@ export function CalculationRulesClient() {
                 {createMut.isPending || updateMut.isPending ? "Saving..." : "Save"}
               </button>
             </div>
-          </div>
-        </div>
+            </div>
+        </>)}
+      </AnimatedModal>
+
+      {confirmDeleteRule && (
+        <ConfirmDialog
+          title="Delete rule"
+          message="Are you sure you want to delete this calculation rule?"
+          confirmLabel="Delete"
+          variant="danger"
+          onConfirm={() => {
+            deleteMut.mutate({ id: confirmDeleteRule });
+            setConfirmDeleteRule(null);
+          }}
+          onCancel={() => setConfirmDeleteRule(null)}
+        />
       )}
     </div>
   );