Tests: Vitest configuration cleanup (#5888)

## Summary

Simplify default scripts. Filtering is still available to users, we can
revisit tagging or grouping later.
This fixes the issue where we had tests that were in the codebase but
never run because they weren't under `/src/components`

Also deletes the duplicate litegraph tests and their associated vitest
config file.

## Changes

- **What**: Test cleanup

## Review Focus

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-5888-Tests-Vitest-configuration-cleanup-2806d73d36508197b800f68f0b028279)
by [Unito](https://www.unito.io)

CONTRIBUTING.md

@@ -213,12 +213,6 @@ Here's how Claude Code can use the Playwright MCP server to inspect the interfac
 - `pnpm i` to install all dependencies
 - `pnpm test:unit` to execute all unit tests
 
-### Component Tests
-
-Component tests verify Vue components in `src/components/`.
-
-- `pnpm test:component` to execute all component tests
-
 ### Playwright Tests
 
 Playwright tests verify the whole app. See [browser_tests/README.md](browser_tests/README.md) for details.
@@ -229,7 +223,6 @@ Before submitting a PR, ensure all tests pass:
 
 ```bash
 pnpm test:unit
-pnpm test:component
 pnpm test:browser
 pnpm typecheck
 pnpm lint