feat: add quantity support to totals, UI, and thread resolution

- totals.service: multiply weight/cost sums by quantity in category and global totals
- setup.service: multiply by quantity in getAllSetups SQL subqueries; expose quantity in getSetupWithItems item list
- thread.service: explicitly pass quantity: 1 when inserting resolved item
- ItemForm: add Quantity number input (min=1, default=1) after price field
- ItemCard: show ×N badge next to item name when quantity > 1
- CollectionView: pass quantity prop to ItemCard in both filtered and grouped views
- $setupId.tsx: pass quantity to ItemCard; multiply by quantity in client-side per-setup totals
- WeightSummaryCard: multiply by quantity in all chart and legend weight calculations
- useItems / useSetups: add quantity to ItemWithCategory / SetupItemWithCategory interfaces

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

src/client/components/ItemForm.tsx

@@ -13,6 +13,7 @@ interface FormData {
 	name: string;
 	weightGrams: string;
 	priceDollars: string;
+	quantity: number;
 	categoryId: number;
 	notes: string;
 	productUrl: string;
@@ -23,6 +24,7 @@ const INITIAL_FORM: FormData = {
 	name: "",
 	weightGrams: "",
 	priceDollars: "",
+	quantity: 1,
 	categoryId: 1,
 	notes: "",
 	productUrl: "",
@@ -49,6 +51,7 @@ export function ItemForm({ mode, itemId }: ItemFormProps) {
 					weightGrams: item.weightGrams != null ? String(item.weightGrams) : "",
 					priceDollars:
 						item.priceCents != null ? (item.priceCents / 100).toFixed(2) : "",
+					quantity: item.quantity ?? 1,
 					categoryId: item.categoryId,
 					notes: item.notes ?? "",
 					productUrl: item.productUrl ?? "",
@@ -98,6 +101,7 @@ export function ItemForm({ mode, itemId }: ItemFormProps) {
 			priceCents: form.priceDollars
 				? Math.round(Number(form.priceDollars) * 100)
 				: undefined,
+			quantity: form.quantity,
 			categoryId: form.categoryId,
 			notes: form.notes.trim() || undefined,
 			productUrl: form.productUrl.trim() || undefined,
@@ -202,6 +206,30 @@ export function ItemForm({ mode, itemId }: ItemFormProps) {
 				)}
 			</div>
 
+			{/* Quantity */}
+			<div>
+				<label
+					htmlFor="item-quantity"
+					className="block text-sm font-medium text-gray-700 mb-1"
+				>
+					Quantity
+				</label>
+				<input
+					id="item-quantity"
+					type="number"
+					min="1"
+					step="1"
+					value={form.quantity}
+					onChange={(e) =>
+						setForm((f) => ({
+							...f,
+							quantity: Math.max(1, Number(e.target.value) || 1),
+						}))
+					}
+					className="w-full px-3 py-2 border border-gray-200 rounded-lg text-sm focus:outline-none focus:ring-2 focus:ring-gray-400 focus:border-transparent"
+				/>
+			</div>
+
 			{/* Category */}
 			<div>
 				<label className="block text-sm font-medium text-gray-700 mb-1">