[RFC] Address under-utilized packages — design-system has 0 imports

## Problem

Several packages in `packages/` appear under-utilized:

- `@comfyorg/design-system` — has **0 imports** from the main app
- `@comfyorg/shared-frontend-utils` — used by only **1 file**
- `@comfyorg/tailwind-utils` — usage unclear

If these packages are not providing value, they add maintenance overhead. If they should be used more widely, there may be code in `src/` that should be consuming them.

## Proposed Investigation

1. Audit each package's purpose and intended consumers
2. For unused packages: determine if they should be deleted or if app code should migrate to use them
3. For `shared-frontend-utils`: identify code in `src/` that duplicates functionality and should import from the package instead
4. For `design-system`: determine if `src/components/ui/` should be consuming it

## Migration Plan

- Audit first, then decide per-package
- Remove unused packages or migrate consumers in separate PRs

┆Issue is synchronized with this [Notion page](https://www.notion.so/Issue-11087-RFC-Address-under-utilized-packages-design-system-has-0-imports-33e6d73d365081f697fff1a5a192bffa) by [Unito](https://www.unito.io)