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/api/me/tokens/route.ts

@@ -9,7 +9,6 @@
 // table has no expires_at column, so it is never read or written here.
 
 import { and, desc, eq } from "drizzle-orm";
-import type { ResultSetHeader } from "mysql2";
 import { apiError, apiJson, apiUnavailable, positiveBigInt } from "@/lib/api";
 import { auth } from "@/lib/auth";
 import { personalTokenScope } from "@/lib/auth/personal-token-scope";
@@ -61,7 +60,7 @@ export async function DELETE(req: Request) {
 	try {
 		// Scope the delete to the owner so users cannot revoke others' tokens.
 		const scope = personalTokenScope(id);
-		const [result] = (await db
+		const [result] = await db
 			.delete(PersonalAccessTokens)
 			.where(
 				and(
@@ -69,7 +68,7 @@ export async function DELETE(req: Request) {
 					eq(PersonalAccessTokens.tokenableId, scope.tokenableId),
 					eq(PersonalAccessTokens.tokenableType, scope.tokenableType),
 				),
-			)) as unknown as [ResultSetHeader];
+			);
 		if (!result.affectedRows) {
 			return apiError("Token not found", 404);
 		}