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/admin-guilds.test.ts

@@ -3,6 +3,7 @@ import { revalidatePath } from "next/cache";
 import { beforeEach, describe, expect, it, vi } from "vitest";
 import { requirePermissionRateLimited } from "@/lib/admin/guard";
 import { logStaffActivity } from "@/lib/services/staff-activity";
+import { fakeForm } from "@/test/fake-form";
 import { disbandGuild } from "./admin-guilds";
 
 const { selectLimit, transactionFn, deleteWhere, updateSet } = vi.hoisted(
@@ -42,10 +43,6 @@ vi.mock("@/lib/services/staff-activity", () => ({ logStaffActivity: vi.fn() }));
 vi.mock("next/cache", () => ({ revalidatePath: vi.fn() }));
 
 const staff = { id: 1, rank: 7, username: "admin" };
-const fakeForm = (data: Record<string, string>) => ({
-	get: (key: string) => data[key] ?? null,
-});
-
 beforeEach(() => {
 	vi.clearAllMocks();
 	vi.mocked(requirePermissionRateLimited).mockResolvedValue(staff as never);
@@ -79,13 +76,13 @@ describe("disbandGuild", () => {
 				await fn(tx);
 			},
 		);
-		await disbandGuild(fakeForm({ id: "1" }) as unknown as FormData);
+		await disbandGuild(fakeForm({ id: "1" }) as FormData);
 		expect(logStaffActivity).toHaveBeenCalled();
 		expect(revalidatePath).toHaveBeenCalledWith("/admin/guilds");
 	});
 
 	it("returns early when id is not positive", async () => {
-		await disbandGuild(fakeForm({ id: "0" }) as unknown as FormData);
+		await disbandGuild(fakeForm({ id: "0" }) as FormData);
 		expect(selectLimit).not.toHaveBeenCalled();
 	});
 });