## What changed
Removed stale `tests-ui` configuration and documentation references from
the repo.
## Why
`tests-ui/` no longer exists, but the repo still carried:
- a dead `@tests-ui/*` tsconfig path
- stale `tests-ui/**/*` include
- a Vite watch ignore for a missing directory
- documentation examples that still referenced the old path
## Validation
- `pnpm format:check`
- `pnpm typecheck`
┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-10736-chore-remove-stale-tests-ui-config-3336d73d3650814a98bedfc113b6eb9b)
by [Unito](https://www.unito.io)
## Summary
Migrates all unit tests from `tests-ui/` to colocate with their source
files in `src/`, improving discoverability and maintainability.
## Changes
- **What**: Relocated all unit tests to be adjacent to the code they
test, following the `<source>.test.ts` naming convention
- **Config**: Updated `vitest.config.ts` to remove `tests-ui` include
pattern and `@tests-ui` alias
- **Docs**: Moved testing documentation to `docs/testing/` with updated
paths and patterns
## Review Focus
- Migration patterns documented in
`temp/plans/migrate-tests-ui-to-src.md`
- Tests use `@/` path aliases instead of relative imports
- Shared fixtures placed in `__fixtures__/` directories
┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-7811-chore-migrate-tests-from-tests-ui-to-colocate-with-source-files-2da6d73d36508147a4cce85365dee614)
by [Unito](https://www.unito.io)
---------
Co-authored-by: Amp <amp@ampcode.com>
Co-authored-by: GitHub Action <action@github.com>
