feat: add dashboard overview stats endpoint and UI integration

- Implemented `GET /dashboard/stats` in `DashboardController` to provide aggregate counts for stock, GRN, and procurement.
- Created `DashboardStatsDto` and `WarehouseValuationDto` to structure the response data.
- Developed `DashboardService` to fetch and compute necessary statistics from the database.
- Added `IDashboardService` interface for service abstraction.
- Introduced API client methods in `dashboard.ts` for frontend consumption of the new endpoint.
- Defined TypeScript types for dashboard data in `dashboard.ts` to ensure type safety in the frontend.
- Updated UI components in the frontend to reflect changes in the dashboard, including styling adjustments and removal of unused icons.

Backend/ERPCore/Dtos/Dashboard/DashboardDtos.cs

@@ -0,0 +1,24 @@
+namespace ERPCore.Dtos.Dashboard;
+
+/// <summary>
+/// Aggregate counts for the dashboard overview — mirrors the widget set in
+/// docs/dashboard-implementation.pdf: reorder alerts, on-hand summary, stock valuation,
+/// pending-approval POs, pending GRNs, open requisitions, open counts awaiting posting,
+/// and open RFQs. Recent movements isn't here — it's just GET /stock/ledger with a small
+/// pageSize, no aggregation needed. A single computed-on-read object, not a stored
+/// entity — same as reorder alerts (docs/11 §5.7).
+/// </summary>
+public sealed record DashboardStatsDto(
+    int LowStockAlerts,
+    decimal OnHandTotal,
+    int OnHandWarehouses,
+    decimal StockValuationTotal,
+    IReadOnlyList<WarehouseValuationDto> StockValuationByWarehouse,
+    int PendingApprovalPurchaseOrders,
+    int PendingGrns,
+    int OpenRequisitions,
+    int PendingCounts,
+    int OpenRfqs);
+
+/// <summary>One bar in the Stock Valuation chart — total FIFO layer value for a warehouse.</summary>
+public sealed record WarehouseValuationDto(int WarehouseId, decimal Total);