feat: add flags Addon to blockVitest (#2072)

## PR Checklist

- [x] Addresses an existing open issue: fixes #2071
- [x] That issue was marked as [`status: accepting
prs`](https://github.com/JoshuaKGoldberg/create-typescript-app/issues?q=is%3Aopen+is%3Aissue+label%3A%22status%3A+accepting+prs%22)
- [x] Steps in
[CONTRIBUTING.md](https://github.com/JoshuaKGoldberg/create-typescript-app/blob/main/.github/CONTRIBUTING.md)
were taken

## Overview

🎁

Author: JoshuaKGoldberg

src/blocks/blockVitest.test.ts

@@ -522,6 +522,7 @@ describe("blockVitest", () => {
 					include: ["src/"],
 				},
 				exclude: ["lib/"],
+				flags: ["--typecheck"],
 			},
 			options: optionsBase,
 		});
@@ -687,7 +688,7 @@ describe("blockVitest", () => {
 			            "vitest": "3.0.9",
 			          },
 			          "scripts": {
-			            "test": "vitest",
+			            "test": "vitest --typecheck",
 			          },
 			        },
 			      },

src/blocks/blockVitest.ts

@@ -29,6 +29,7 @@ export const blockVitest = base.createBlock({
 			})
 			.default({}),
 		exclude: z.array(z.string()).default([]),
+		flags: z.array(z.string()).default([]),
 	},
 	produce({ addons }) {
 		const { actionSteps, coverage, exclude = [] } = addons;
@@ -153,7 +154,7 @@ describe(greet, () => {
 							"vitest",
 						),
 						scripts: {
-							test: "vitest",
+							test: `vitest ${addons.flags.join(" ")}`.trim(),
 						},
 					},
 				}),