fix: hard-invalidate importers when dependency is deleted (#23527)

[mystmn]

Description

Fixes #23527.

When a module file (e.g. src/dep.ts) is renamed (e.g. to src/dep.tsx) or deleted while the dev server is running, any importer statically importing that module (e.g. import { value } from "./dep") was being soft-invalidated instead of hard-invalidated.

Because importer.staticImportedUrls?.has(mod.url) evaluated to true, Vite soft-invalidated the importer, preserving its cached transformed code with the old resolved URL (/src/dep.ts) and appending an HMR timestamp (/src/dep.ts?t=...). Requesting that stale URL failed with a pre-transform error (Does the file exist?).

This PR:

1. Marks module nodes as isDeleted in onFileDelete and ensures they are invalidated in the module graph.
2. Prevents soft-invalidation of importers when the imported module was deleted (!mod.isDeleted). Importers are now hard-invalidated so that their import specifiers are re-transformed and re-resolved against the filesystem.
3. In propagateUpdate, ensures deleted modules cannot self-accept or be accepted via acceptedHmrDeps, propagating to importers and falling back to a full reload.
4. Resets isDeleted = false on file creation/change or when re-ensuring the entry in the module graph.
5. Adds unit tests covering importer hard-invalidation on file deletion.