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/analytics/page.tsx

@@ -12,7 +12,7 @@ import { redirect } from "next/navigation";
 import { getLocale, getTranslations } from "next-intl/server";
 import { StatsCard } from "@/components/admin/stats-card";
 import { Card, CardContent, CardHeader, CardTitle } from "@/components/ui/card";
-import { Ban, db, Rooms, RoomTradeLog, User } from "@/lib/db";
+import { Ban, db, queryRows, Rooms, RoomTradeLog, User } from "@/lib/db";
 import { canAccess, getAdminContext, PERMS } from "@/lib/permissions";
 import { redisCache } from "@/lib/redis-cache";
 
@@ -82,8 +82,7 @@ async function safeCount(
 }
 
 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);
 }
 
 async function getAnalyticsData(