test: lint against module-scope vi.stubGlobal and vi.spyOn

## Problem

Once #14836 lands, `unstubGlobals` and `restoreMocks` silently disarm any stub or spy installed at module scope. The reset runs in `onBeforeTryTask`, which is before the first test of every file, so a module scope `vi.stubGlobal` or `vi.spyOn` is gone by the time any test body runs.

Most instances fail loudly and get caught. The dangerous ones do not:

- a stub whose only assertion is negative (`expect(fetchMock).not.toHaveBeenCalled()`) becomes vacuously true and passes forever
- a `vi.stubGlobal('fetch', ...)` that dies means the test issues a real network request instead

Both shapes were live in #14836 and were only found by hand (`initHostTelemetry.test.ts`, `LogsTerminal.test.ts`, `authStore.test.ts`). There is nothing stopping the next one.

## Suggested fix

Lint for it. Something like this in `eslint.config.ts`, scoped to test files:

```js
'no-restricted-syntax': [
'error',
{
selector: "Program > ExpressionStatement > CallExpression[callee.object.name='vi'][callee.property.name=/^(stubGlobal|spyOn)$/]",
message: 'Install stubs and spies in beforeEach. unstubGlobals and restoreMocks remove module scope ones before each test.'
}
]
```

Also worth covering `const x = vi.spyOn(...)` at module scope, which is the same hazard with an extra failure mode: the handle survives and can be re-armed in `beforeEach`, but it is detached from the object, so the real method runs and the spy records nothing. That was the `downloadUtil.test.ts` case.

After #14836 the rule should be close to clean, so adoption is cheap.

## Context

Found while reviewing #14836. Not blocking that PR.

Start in eslint.config.ts and inspect how rules are scoped to test files. Review the mentioned cases in initHostTelemetry.test.ts, LogsTerminal.test.ts, authStore.test.ts, and downloadUtil.test.ts, then run the repository lint command. Done means module-scope vi.stubGlobal and vi.spyOn usages, including assigned spy handles, are reported and the existing test files are clean.

Written by the indexing model from the issue text.