Create skill endorsements and verification system

[hizxle]

As a user, I want to endorse others' skills and have my skills endorsed or verified, so that I can build credibility and validate my expertise.

Tasks:

• [ ] Implement a "+1" endorsement button for each skill on user profiles
• [ ] Create a model to store skill endorsements
• [ ] Display the number of endorsements next to each skill
• [ ] Develop a system for skill verification (e.g., integration with online course platforms)
• [ ] Implement visual indicators for verified skills (e.g., badges or icons)