Phase H: Add Cash Flow Statement (direct / cash-basis method)

- CashFlowStatementDto (Operating, Investing, Financing sections; BeginningCash/EndingCash)
- CashFlowLineDto for Investing/Financing line items
- GetCashFlowStatementAsync on IFinancialReportService + implementation in FinancialReportService
- GenerateCashFlowStatementPdfAsync on IPdfService + QuestPDF implementation in PdfService
- ReportsController.CashFlowStatement GET + CashFlowStatementPdf GET with inline/download mode
- CashFlowStatement.cshtml view with date filter, 3-section cards, summary sidebar, methodology note
- Reports Landing page: Cash Flow Statement card added to Accounting section

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

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

@@ -204,6 +204,14 @@
             <p>All active accounts with debit and credit balances — validates that your books are in balance.</p>
             <div class="report-arrow">Open report <i class="bi bi-arrow-right"></i></div>
         </a>
+        <a asp-controller="Reports" asp-action="CashFlowStatement" class="report-card">
+            <div class="report-card-icon" style="background:#ecfeff;color:#0891b2;">
+                <i class="bi bi-water"></i>
+            </div>
+            <h5>Cash Flow Statement</h5>
+            <p>Track actual cash in/out across operating, investing, and financing activities with beginning and ending cash balance.</p>
+            <div class="report-arrow">Open report <i class="bi bi-arrow-right"></i></div>
+        </a>
     </div>
 </div>
 }