chore: migrate tests from tests-ui/ to colocate with source files (#7811)

## 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>

tests-ui/tests/platform/workflow/cloud/getWorkflowFromHistory.test.ts

@@ -1,111 +0,0 @@
-import { describe, expect, it, vi } from 'vitest'
-
-import type { ComfyWorkflowJSON } from '@/platform/workflow/validation/schemas/workflowSchema'
-import { getWorkflowFromHistory } from '@/platform/workflow/cloud/getWorkflowFromHistory'
-
-const mockWorkflow: ComfyWorkflowJSON = {
-  id: 'test-workflow-id',
-  revision: 0,
-  last_node_id: 5,
-  last_link_id: 3,
-  nodes: [],
-  links: [],
-  groups: [],
-  config: {},
-  extra: {},
-  version: 0.4
-}
-
-const mockHistoryResponse = {
-  'test-prompt-id': {
-    prompt: {
-      priority: 1,
-      prompt_id: 'test-prompt-id',
-      extra_data: {
-        client_id: 'test-client',
-        extra_pnginfo: {
-          workflow: mockWorkflow
-        }
-      }
-    },
-    outputs: {},
-    status: {
-      status_str: 'success',
-      completed: true,
-      messages: []
-    }
-  }
-}
-
-describe('getWorkflowFromHistory', () => {
-  it('should fetch workflow from /history_v2/{prompt_id} endpoint', async () => {
-    const mockFetchApi = vi.fn().mockResolvedValue({
-      json: async () => mockHistoryResponse
-    })
-
-    await getWorkflowFromHistory(mockFetchApi, 'test-prompt-id')
-
-    expect(mockFetchApi).toHaveBeenCalledWith('/history_v2/test-prompt-id')
-  })
-
-  it('should extract and return workflow from response', async () => {
-    const mockFetchApi = vi.fn().mockResolvedValue({
-      json: async () => mockHistoryResponse
-    })
-
-    const result = await getWorkflowFromHistory(mockFetchApi, 'test-prompt-id')
-
-    expect(result).toEqual(mockWorkflow)
-  })
-
-  it('should return undefined when prompt_id not found in response', async () => {
-    const mockFetchApi = vi.fn().mockResolvedValue({
-      json: async () => ({})
-    })
-
-    const result = await getWorkflowFromHistory(mockFetchApi, 'nonexistent-id')
-
-    expect(result).toBeUndefined()
-  })
-
-  it('should return undefined when workflow is missing from extra_pnginfo', async () => {
-    const mockFetchApi = vi.fn().mockResolvedValue({
-      json: async () => ({
-        'test-prompt-id': {
-          prompt: {
-            priority: 1,
-            prompt_id: 'test-prompt-id',
-            extra_data: {
-              client_id: 'test-client'
-            }
-          },
-          outputs: {}
-        }
-      })
-    })
-
-    const result = await getWorkflowFromHistory(mockFetchApi, 'test-prompt-id')
-
-    expect(result).toBeUndefined()
-  })
-
-  it('should handle fetch errors gracefully', async () => {
-    const mockFetchApi = vi.fn().mockRejectedValue(new Error('Network error'))
-
-    const result = await getWorkflowFromHistory(mockFetchApi, 'test-prompt-id')
-
-    expect(result).toBeUndefined()
-  })
-
-  it('should handle malformed JSON responses', async () => {
-    const mockFetchApi = vi.fn().mockResolvedValue({
-      json: async () => {
-        throw new Error('Invalid JSON')
-      }
-    })
-
-    const result = await getWorkflowFromHistory(mockFetchApi, 'test-prompt-id')
-
-    expect(result).toBeUndefined()
-  })
-})