refactor(db): typed query helpers, shared test FormData helper

Replace raw db.execute tuple casts with queryRows/rowsFrom/execResult/
affectedRows helpers from lib/db, drop redundant mysql2 casts on typed
query builders, and centralize per-test fakeForm into test/fake-form.
Update db mocks in tests so helpers resolve against mocked execute.

src/actions/catalog-items.ts

@@ -11,7 +11,7 @@ import {
 } from "@/features/catalog/server/offer-commands";
 import { sendCatalogUpdate } from "@/features/catalog/server/sync-status";
 import { requirePermission } from "@/lib/admin/guard";
-import { CatalogItems, db, ItemsBase } from "@/lib/db";
+import { CatalogItems, db, ItemsBase, queryRows } from "@/lib/db";
 import { PERMS } from "@/lib/permissions";
 import { logAudit } from "@/lib/services/audit";
 import { withCatalogExport } from "@/lib/services/catalog-git-queue";
@@ -145,10 +145,10 @@ export async function bulkCreateCatalogItems({
 		let failed = 0;
 
 		// Find the next order number on the target page to avoid collisions.
-		const [maxOrder] = (await db.execute(sql`
+		const maxOrder = await queryRows<{ maxOrder: number }>(sql`
 			SELECT COALESCE(MAX(order_number), 0) AS maxOrder FROM catalog_items WHERE page_id = ${String(pageId)}
-		`)) as unknown as [{ maxOrder: number }, unknown];
-		let nextOrder = Number(maxOrder?.maxOrder ?? 0) + 1;
+		`);
+		let nextOrder = Number(maxOrder[0]?.maxOrder ?? 0) + 1;
 
 		for (const row of rows) {
 			const base = baseMap.get(row.baseId);