fix: Add JSON import assertions for Node.js ESM compatibility (#5507)

Added `with { type: 'json' }` assertions to all JSON imports to ensure compatibility with Node.js ES modules and Playwright environments. This follows the current ESM specification where JSON imports require explicit type assertions.

Affected areas:
- Tailwind config
- i18n locale imports (36 files)
- Test fixtures and spec files
- API client feature flags
- Core color palettes

References:
- https://nodejs.org/api/esm.html
- https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/import/with

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

Co-authored-by: Claude <noreply@anthropic.com>

src/scripts/api.ts

@@ -1,7 +1,7 @@
 import axios from 'axios'
 import { get } from 'es-toolkit/compat'
 
-import defaultClientFeatureFlags from '@/config/clientFeatureFlags.json'
+import defaultClientFeatureFlags from '@/config/clientFeatureFlags.json' with { type: 'json' }
 import type {
   DisplayComponentWsMessage,
   EmbeddingsResponse,