[bugfix] Add vite-define shim for Playwright i18n collection (#6906)

## Summary

Fixes the `ReferenceError: __DISTRIBUTION__ is not defined` error when
running i18n collection tests.

## Problem

PR #6879 added conditional menu commands based on distribution (hiding
memory unload commands in cloud). This introduced a dependency on
`isCloud` which uses the `__DISTRIBUTION__` Vite define variable in
`coreMenuCommands.ts`.

When Playwright's test runner imports this file during i18n collection,
it fails because Vite define variables are only replaced during Vite's
build/dev process, not during Playwright's TypeScript compilation.

## Solution

Created a simple shim (`scripts/vite-define-shim.ts`) that:
1. Defines all Vite define variables as global constants with default
values
2. Provides a minimal `window` shim for Node environment
3. Is imported at the top of `collect-i18n-general.ts` before any code
that uses these variables

This approach is simpler than:
- Creating a custom Babel plugin (attempted in this PR, see commit
history)
- Using `ctViteConfig` (only works for component testing, not regular
Playwright tests)
- Post-build regex replacement (fragile and error-prone)

## Test Plan

Run `pnpm collect-i18n` and verify:
- ✅ No more `ReferenceError: __DISTRIBUTION__ is not defined`
- ✅ No more `ReferenceError: window is not defined`
- ⏱️ Tests may timeout if dev server is not running on port 5173, but
that's a separate issue

## Related

- Fixes issue introduced by PR #6879
- Related to Notion task:
https://www.notion.so/comfy-org/Implement-Babel-plugin-for-Vite-define-replacements-in-Playwright-2b56d73d365081d5bb63e02712912b17

🤖 Generated with [Claude Code](https://claude.com/claude-code)

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-6906-bugfix-Add-vite-define-shim-for-Playwright-i18n-collection-2b66d73d36508182b4d6d69b88ae2771)
by [Unito](https://www.unito.io)

---------

Co-authored-by: Claude <noreply@anthropic.com>
Co-authored-by: github-actions <github-actions@github.com>
Co-authored-by: Alexander Brown <drjkl@comfy.org>
Co-authored-by: coderabbitai[bot] <136622811+coderabbitai[bot]@users.noreply.github.com>

scripts/collect-i18n-general.ts

@@ -1,5 +1,8 @@
 import * as fs from 'fs'
 
+// Import Vite define shim to make __DISTRIBUTION__ and other define variables available
+import './vite-define-shim'
+
 import { DESKTOP_DIALOGS } from '../apps/desktop-ui/src/constants/desktopDialogs'
 import { comfyPageFixture as test } from '../browser_tests/fixtures/ComfyPage'
 import {