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/app/admin/users/_lib/load-user-overview.test.ts

@@ -7,7 +7,10 @@ const state = vi.hoisted(() => ({
 	allowed: new Set<string>(),
 	execute: vi.fn(),
 }));
-vi.mock("@/lib/db", () => ({ db: { execute: state.execute } }));
+vi.mock("@/lib/db", async () => ({
+	...(await import("@/test/db-helpers")).createDbHelpers(state.execute),
+	db: { execute: state.execute },
+}));
 vi.mock("@/lib/permissions", async () => ({
 	...(await import("@/lib/permission-slugs")),
 	canAccess: (_: unknown, permission: string) => state.allowed.has(permission),

src/app/admin/users/_lib/load-user-overview.ts

@@ -1,5 +1,5 @@
 import { type SQL, sql } from "drizzle-orm";
-import { db } from "@/lib/db";
+import { queryRows } from "@/lib/db";
 import { canAccess, PERMS, type PermissionSet } from "@/lib/permissions";
 
 export type OverviewRow = {
@@ -27,8 +27,7 @@ export async function loadUserOverview(
 	rank: number,
 ): Promise<OverviewSection[]> {
 	const read = async (query: SQL): Promise<OverviewRow[]> => {
-		const [rows] = await db.execute(query);
-		return rows as unknown as OverviewRow[];
+		return queryRows<OverviewRow>(query);
 	};
 	const sources: {
 		key: string;

src/app/admin/users/_lib/load-user.test.ts

@@ -11,54 +11,56 @@ vi.mock("next/navigation", () => ({
 		throw new Error("not found");
 	},
 }));
-vi.mock("@/lib/db", () => {
+vi.mock("@/lib/db", async () => {
 	const tables = Object.fromEntries(
 		["User", "Rooms", "RoomTradeLog", "UsersBadges", "UsersCurrency"].map(
 			(name) => [name, { name }],
 		),
 	);
+	const db = {
+		select() {
+			let name = "";
+			const rows = () =>
+				name === "User"
+					? [{ id: 42, username: "User", rank: 2, online: "0" }]
+					: [];
+			const query = {
+				from(table: { name: string }) {
+					name = table.name;
+					state.tables.push(name);
+					return query;
+				},
+				where() {
+					return query;
+				},
+				orderBy() {
+					return query;
+				},
+				limit() {
+					return query;
+				},
+				// biome-ignore lint/suspicious/noThenProperty: Drizzle queries are intentionally awaitable.
+				then(resolve: (value: unknown[]) => unknown) {
+					return Promise.resolve(rows()).then(resolve);
+				},
+				catch() {
+					return Promise.resolve(rows());
+				},
+			};
+			return query;
+		},
+		async execute(query: Parameters<MySqlDialect["sqlToQuery"]>[0]) {
+			const compiled = new MySqlDialect().sqlToQuery(query).sql;
+			state.sql.push(compiled);
+			if (state.failLogs && compiled.includes("chatlogs_room"))
+				throw new Error("unavailable");
+			return [[], []];
+		},
+	};
 	return {
 		...tables,
-		db: {
-			select() {
-				let name = "";
-				const rows = () =>
-					name === "User"
-						? [{ id: 42, username: "User", rank: 2, online: "0" }]
-						: [];
-				const query = {
-					from(table: { name: string }) {
-						name = table.name;
-						state.tables.push(name);
-						return query;
-					},
-					where() {
-						return query;
-					},
-					orderBy() {
-						return query;
-					},
-					limit() {
-						return query;
-					},
-					// biome-ignore lint/suspicious/noThenProperty: Drizzle queries are intentionally awaitable.
-					then(resolve: (value: unknown[]) => unknown) {
-						return Promise.resolve(rows()).then(resolve);
-					},
-					catch() {
-						return Promise.resolve(rows());
-					},
-				};
-				return query;
-			},
-			async execute(query: Parameters<MySqlDialect["sqlToQuery"]>[0]) {
-				const compiled = new MySqlDialect().sqlToQuery(query).sql;
-				state.sql.push(compiled);
-				if (state.failLogs && compiled.includes("chatlogs_room"))
-					throw new Error("unavailable");
-				return [[], []];
-			},
-		},
+		db,
+		...(await import("@/test/db-helpers")).createDbHelpers(db.execute),
 	};
 });
 

src/app/admin/users/_lib/load-user.ts

@@ -2,6 +2,7 @@ import { asc, count, desc, eq, or, sql } from "drizzle-orm";
 import { notFound } from "next/navigation";
 import {
 	db,
+	queryRows,
 	Rooms,
 	RoomTradeLog,
 	User,
@@ -10,8 +11,7 @@ import {
 } from "@/lib/db";
 
 async function rawRows<T>(query: ReturnType<typeof sql>): Promise<T[]> {
-	const [rows] = (await db.execute(query)) as unknown as [T[], unknown];
-	return rows ?? [];
+	return queryRows<T>(query);
 }
 
 export async function loadUserById(