Feat/research slender lending protocol

[Obiajulu-gif]

This pull request updates the contributor documentation and adds two new research profiles for DeFi protocols on Stellar. The most important changes are the addition of detailed research markdown files for FxDAO and Slender, as well as improvements to the formatting and content of the CONTRIBUTORS.md file.

New DeFi protocol research profiles:

• Added a new research profile for FxDAO, a Stellar-native borrowing protocol using collateralized debt positions and synthetic stablecoins, including protocol details, contract/account IDs, risk model, and sources. (web/research/fxdao.md)
• Added a new research profile for Slender, a Soroban-based pooled lending and borrowing protocol with flash loans, including configuration, risk model, contract/account IDs, and sources. (web/research/slender.md)

Improvements to contributor documentation:

• Standardized the separator in contributor role descriptions from an em dash to a hyphen for consistency and clarity throughout the CONTRIBUTORS.md file. [1] [2] [3]
• Added two new contributor entries for research on FxDAO and Slender, crediting Obiajulu-gif for these submissions.
• Minor formatting fixes and consolidation of badge/link markup in the contributor table for improved readability and maintainability. [1] [2]
• Updated the roles section in CONTRIBUTORS.md to use hyphens instead of em dashes for consistency.
  Closes Research & Upload a Stellar Wave Lending or Borrowing Protocol #19

[vercel]

@Obiajulu-gif is attempting to deploy a commit to the webverse Team on Vercel.

A member of the Team first needs to authorize it.

[samieazubike]

You haven't satisfied all conditions for this issue

[Obiajulu-gif]

@samieazubike i have fix the error

[Obiajulu-gif]

@samieazubike please merge my code