Add SnapAPI — multi-tool developer utility REST API

[niklastmk]

What

Adds SnapAPI to the collection via a new collection/snapapi.yaml file.

About SnapAPI

SnapAPI is a multi-tool REST API for developers. Instead of signing up for separate services for QR codes, screenshots, image processing, and other utility functions, SnapAPI provides 13+ endpoints behind a single API key:

• QR Code Generation — PNG/SVG with custom colors and sizes
• Screenshot Capture — full-page screenshots of any URL
• Image Resize & Convert — PNG, WebP, JPEG, AVIF
• HTML to PDF — convert HTML content to downloadable PDFs
• Hash Generation — SHA-256, SHA-512, MD5, and more
• UUID / ID Generation — UUIDs, nanoids, hex tokens with prefixes
• URL Metadata Extraction — Open Graph tags, titles, favicons
• Base64 Encode/Decode, JWT Decode, Color Conversion, Lorem Ipsum, Markdown to HTML, Placeholder Images

Field	Value
Auth	API Key (Bearer token)
HTTPS	Yes
CORS	Yes
Free tier	100 calls/month, no credit card
Docs	https://snapapi-production-3fa2.up.railway.app/docs

Note on build step

The CONTRIBUTING.md mentions running npm run build to regenerate the README. I've added the YAML file. If maintainers prefer I also run the build and include the README diff, please let me know — happy to update the PR. Otherwise, if the CI pipeline handles it automatically, the YAML alone should be sufficient.