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-teams.test.ts

@@ -2,6 +2,7 @@
 import { revalidatePath } from "next/cache";
 import { beforeEach, describe, expect, it, vi } from "vitest";
 import { requirePermission } from "@/lib/admin/guard";
+import { fakeForm } from "@/test/fake-form";
 import { createTeam, deleteTeam } from "./admin-teams";
 
 const { insertValues, deleteWhere } = vi.hoisted(() => {
@@ -22,10 +23,6 @@ vi.mock("@/lib/db", () => ({
 vi.mock("next/cache", () => ({ revalidatePath: vi.fn() }));
 
 const staff = { id: 1, rank: 7, username: "admin" };
-const fakeForm = (data: Record<string, string | null>) => ({
-	get: (key: string) => (key in data ? data[key] : null),
-});
-
 beforeEach(() => {
 	vi.clearAllMocks();
 	vi.mocked(requirePermission).mockResolvedValue(staff as never);
@@ -35,9 +32,7 @@ beforeEach(() => {
 
 describe("createTeam", () => {
 	it("creates a team entry", async () => {
-		await createTeam(
-			fakeForm({ rankName: "Moderator" }) as unknown as FormData,
-		);
+		await createTeam(fakeForm({ rankName: "Moderator" }) as FormData);
 		expect(insertValues).toHaveBeenCalledWith(
 			expect.objectContaining({ rankName: "Moderator" }),
 		);
@@ -45,14 +40,14 @@ describe("createTeam", () => {
 	});
 
 	it("returns early when rankName is empty", async () => {
-		await createTeam(fakeForm({ rankName: "" }) as unknown as FormData);
+		await createTeam(fakeForm({ rankName: "" }) as FormData);
 		expect(insertValues).not.toHaveBeenCalled();
 	});
 });
 
 describe("deleteTeam", () => {
 	it("deletes a team entry", async () => {
-		await deleteTeam(fakeForm({ id: "42" }) as unknown as FormData);
+		await deleteTeam(fakeForm({ id: "42" }) as FormData);
 		expect(deleteWhere).toHaveBeenCalled();
 		expect(revalidatePath).toHaveBeenCalledWith("/admin/teams");
 	});