Enable --typecheck by default?

Clear and concise description of the problem

Right now, if you want to use the awesome new Testing Types, you have to provide a manual --typecheck:

npx vitest --typecheck

I think we can assume many types testing users go with the default behavior of putting all types tests in .test-d.ts files:

 ✓ src/a.test.ts (9 tests) 5ms
 ✓ src/b.test.ts (10 tests) 6ms
 ✓  TS  src/c.test-d.ts (0 test)

Suggested solution

How about enabling --typecheck by default?

Alternative

Or, failing that, some subset of --typecheck that does not impact non-*.test-d.ts files? I'll admit I'm not deeply familiar with the mode to know if there's some conflict.

Additional context

No response

Validations

• Follow our Code of Conduct
• Read the Contributing Guidelines.
• Read the docs.
• Check that there isn't already an issue that request the same feature to avoid creating a duplicate.

Start by reading the Testing Types guide and running the documented npx vitest --typecheck example. Trace where the --typecheck CLI option is configured and check how .test-d.ts files are handled. Done means type checking is enabled by default without changing behavior for regular test files, or the supported subset is clearly defined and tested.