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/lib/litegraph/test/testExtensions.ts

@@ -7,10 +7,10 @@ import type {
   ISerialisedGraph,
   SerialisableGraph
 } from '../src/types/serialisation'
-import floatingBranch from './assets/floatingBranch.json'
-import floatingLink from './assets/floatingLink.json'
-import linkedNodes from './assets/linkedNodes.json'
-import reroutesComplex from './assets/reroutesComplex.json'
+import floatingBranch from './assets/floatingBranch.json' with { type: 'json' }
+import floatingLink from './assets/floatingLink.json' with { type: 'json' }
+import linkedNodes from './assets/linkedNodes.json' with { type: 'json' }
+import reroutesComplex from './assets/reroutesComplex.json' with { type: 'json' }
 import {
   basicSerialisableGraph,
   minimalSerialisableGraph,