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/features/catalog/server/bulk-undo.test.ts

@@ -10,7 +10,8 @@ const state = vi.hoisted(() => ({
 	audit: [] as unknown[],
 	queries: [] as string[],
 }));
-vi.mock("@/lib/db", () => ({
+vi.mock("@/lib/db", async () => ({
+	rowsFrom: (await import("@/test/db-helpers")).rowsFrom,
 	db: {
 		transaction: async (fn: (tx: unknown) => Promise<unknown>) => {
 			const saved = structuredClone(state.current);
@@ -79,8 +80,9 @@ vi.mock("@/lib/db", () => ({
 	},
 }));
 
-vi.mock("@/features/operations/server", async () => {
-	const { db } = await import("@/lib/db");
+import { db } from "@/lib/db";
+
+vi.mock("@/features/operations/server", () => {
 	return {
 		runOperation: (
 			_input: unknown,