Add 4 AI bookkeeping features

Feature 7: Bank Rec Auto-Match — AiSuggestMatches endpoint scores uncleared
transactions vs statement ending balance; AI Auto-Match panel in Reconcile.cshtml
with confidence highlights and Apply All button.

Feature 8: Late Payment Prediction — PredictLatePayments endpoint scores open AR
customers by risk (high/medium/low) using historical avg-days-to-pay + late rate;
rendered as badge table in AR Aging view via ar-aging-ai.js.

Feature 9: Natural Language Financial Queries — FinancialQuery GET page + RunFinancialQuery
POST; 12-month context snapshot pre-loaded; answers grounded in real data with
supporting facts, follow-up suggestions, session history, and example chips.

Feature 10: Recurring Bill Detection — RunRecurringDetection scans 12 months of bills
for vendor payment patterns (monthly/quarterly/annual); card grid view in Bills/RecurringDetection.cshtml
with confidence badges, next-expected-date, and suggested actions.

Supporting: 4 new DTO groups in AccountingAiDtos.cs, 4 method signatures in
IAccountingAiService.cs, 4 implementations in AccountingAiService.cs, 4 new
AiFeatures constants, 2 new Landing page AI report cards.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/PowderCoating.Web/Views/Reports/ArAging.cshtml

@@ -240,3 +240,42 @@ else
     <i class="bi bi-info-circle me-1"></i>
     Generated @DateTime.Now.ToString("MMM d, yyyy h:mm tt") · Includes all open invoices (excluding Draft and Voided). Age calculated from due date.
 </div>
+
+@if (Model.Customers.Any())
+{
+<!-- AI Late Payment Prediction -->
+<div class="card shadow-sm mt-4 border-0 no-print" id="aiRiskCard">
+    <div class="card-header d-flex align-items-center gap-2">
+        <i class="bi bi-robot text-primary"></i>
+        <span class="fw-semibold">AI Payment Risk Prediction</span>
+        <button id="aiRiskBtn" class="btn btn-sm btn-outline-primary ms-auto">
+            <i class="bi bi-magic me-1"></i>Predict Payment Risk
+        </button>
+    </div>
+    <div class="card-body d-none" id="aiRiskBody">
+        <div id="aiRiskSpinner" class="text-center py-3 d-none">
+            <div class="spinner-border text-primary" role="status"></div>
+            <p class="text-muted mt-2 small">Claude is analyzing payment behavior…</p>
+        </div>
+        <div id="aiRiskError" class="alert alert-danger alert-permanent d-none"></div>
+        <div id="aiRiskInsights" class="text-muted small mb-3"></div>
+        <div id="aiRiskTable" class="table-responsive d-none">
+            <table class="table table-sm align-middle">
+                <thead class="table-light">
+                    <tr>
+                        <th>Customer</th>
+                        <th>Risk</th>
+                        <th>Est. Days to Payment</th>
+                        <th>Reasoning</th>
+                    </tr>
+                </thead>
+                <tbody id="aiRiskRows"></tbody>
+            </table>
+        </div>
+    </div>
+</div>
+}
+
+@section Scripts {
+<script src="/js/ar-aging-ai.js"></script>
+}