feat: add admin dashboard summary

Add seller-scoped dashboard aggregation and API, private financial summary DTOs, responsive admin metrics, and authenticated E2E coverage.

packages/contracts/dashboard.js

@@ -0,0 +1,21 @@
+export function toAdminDashboardDto(dashboard) {
+  return {
+    counts: dashboard.counts,
+    financials: dashboard.financials,
+    recentSales: dashboard.recentSales.map(({ sale, saleItem, inventoryItem, productName, netProceedsMinor, profitMinor }) => ({
+      id: sale.id,
+      productName: productName ?? inventoryItem.id,
+      saleDate: sale.saleDate,
+      soldPriceMinor: sale.soldPriceMinor,
+      netProceedsMinor,
+      profitMinor,
+      inventoryItemId: saleItem.inventoryItemId,
+    })),
+    recentAcquisitions: dashboard.recentAcquisitions.map((acquisition) => ({
+      id: acquisition.id,
+      inventoryItemId: acquisition.inventoryItemId,
+      date: acquisition.date ?? null,
+      costBasisMinor: acquisition.costBasisMinor ?? null,
+    })),
+  };
+}

packages/contracts/package.json

@@ -5,6 +5,7 @@
   "exports": {
     "./auth": "./auth.js",
     "./acquisition": "./acquisition.js",
+    "./dashboard": "./dashboard.js",
     "./inventory": "./inventory.js",
     "./image": "./image.js",
     "./listing": "./listing.js",