Add QuantLink to Commercial & Proprietary Services

[robertwills-quantlink]

Adds one entry for QuantLink (https://www.quantlink.ai) to the Commercial & Proprietary Services section.

Per CONTRIBUTING, QuantLink is a proprietary SaaS (commercial website, no public source repo), so it belongs in Commercial & Proprietary Services rather than a code-library category. It sits alongside existing peers there such as StockVektor, 13F Insight, and VertData.

QuantLink is an AI-powered US-equity research terminal: a fundamental and technical stock screener with backtesting, AI deep-research grounded in SEC filings, institutional 13F holder analysis, insider (Form 4) activity, and congressional/politician trade tracking from STOCK Act disclosures. It has a usable free tier.

• One entry, added at the end of the section, format matches the surrounding entries.
• Not a duplicate (searched the list; no existing QuantLink entry).
• Website is live and https.

Made with Cursor

[wilsonfreitas]

Thanks for the contribution. Please rebase this branch onto the current main; the current validation failure comes from an unrelated duplicate pmxt entry carried by the stale branch. Because QuantLink is a repository-less commercial service, please also link to public documentation of the exact permanent free-tier limits and confirm whether payment information is required. The entry can remain under Commercial & Proprietary Services.