Extract shared utilities into workspace package (#5843)

## Summary

Extracts shared formatting and network utilities into dedicated
workspace package.

## Changes

- **What**: Created `@comfyorg/shared-frontend-utils` package containing
formatUtil and networkUtil
- **Breaking**: None - utilities remain accessible via path aliases in
`tsconfig`

Split `createAnnotatedPath` and `electronMirrorCheck` out and left in
frontend, due to their tightly-coupled nature. See [discussion on this
PR](https://github.com/Comfy-Org/ComfyUI_frontend/pull/5843#issuecomment-3344724727).

vitest.config.ts

@@ -37,6 +37,9 @@ export default defineConfig({
   },
   resolve: {
     alias: {
+      '@/utils/formatUtil': '/packages/shared-frontend-utils/src/formatUtil.ts',
+      '@/utils/networkUtil':
+        '/packages/shared-frontend-utils/src/networkUtil.ts',
       '@': '/src'
     }
   },