feat(comfyui): Add ComfyUI Registry service, tests, fixture and docs

[neverbiasu]

Summary
Add ComfyUI Registry badges (downloads, version, stars) with a resilient fetcher, tests, fixture and docs.

What this PR does

• Implements service: comfyui-registry.service.js
  • Routes: /comfyui/:node/downloads, /comfyui/:node/version, /comfyui/:node/stars
  • Respects upstream Cache-Control max-age, supports ETag conditional GET (304), and uses a conservative fallback TTL when max-age=0 and no ETag.
  • Inflight request coalescing and retry with exponential backoff on network/5xx errors.
  • Version badge uses the node identifier as the label (e.g. comfyui-image-captioner).
• Tests + fixture: comfyui-registry.spec.js, comfyui_node.json
• Docs: comfyui-registry.md (usage & implementation notes)
• Removed root-level legacy placeholders to avoid duplicate exports.

Testing (local)

• Focused unit tests:
  NODE_CONFIG_ENV=test npx mocha comfyui-registry.spec.js --timeout 5000
  -> 3 passing locally
• Configurable fallback TTL: set COMFYUI_FALLBACK_TTL (seconds) for testing behavior when upstream returns max-age=0 without ETag.

Notes for reviewers

• Please check caching/ETag logic and error mapping (404 -> NotFound, 401/403 -> Inaccessible).
• Verify doc examples and the new short-route contract.
• No PRD/DEV/TODO drafts are included in this PR by request.

Changelog entry

• Added: ComfyUI Registry badges (downloads, version, stars) with caching and ETag revalidation.

[github-actions]

	Warnings
⚠️	Found badge URL that may not follow our standard route abbreviations. Please ensure you've reviewed our conventions
⚠️	Found badge URL that may not follow our standard route abbreviations. Please ensure you've reviewed our conventions

	Messages
📖	✨ Thanks for your contribution to Shields, @neverbiasu!
📖	Thanks for contributing to our documentation. We ❤️ our documentarians!

Generated by 🚫 dangerJS against 063c84e

[neverbiasu]

@PyvesB Hii, could you review my code.

[PyvesB]

Hello @neverbiasu 👋🏻 What is the rationale for adding a cache layer for this badge? We typically cache at the CDN layer, which has the advantage of being shared across all running Shields.io instances and completely bypasses any processing.

[neverbiasu]

Hii, @PyvesB. Thx for your suggestions. I will try to use it.

[PyvesB]

I'd suggest following our tutorial and generally speaking keeping things as simple as possible: https://github.com/badges/shields/blob/master/doc/TUTORIAL.md

By the way, do you have any information on the API's rate limits?

[neverbiasu]

@PyvesB Thx for the suggestions, I have rewrite in the format mentioned in TUTOTIAL.md. I didn't know the API's rate limits but I can ask the backend dev of ComfyUI and answer it later.