feat(api): add recruiter talent search

[Aneesh-0108]

Overview

Implements GitHub Issue #28: Recruiter Talent Search.

Implemented

• Added GET /api/talents for paginated student talent discovery
• Added filtering by skills, open-to-work status, DK24 verification status, and graduation year
• Added free-text search across profile, skills, and project content
• Added support for matching multiple skills using all or any
• Included relevant skills, projects, and project technologies in the results
• Added input validation, sorting, and pagination
• Added backend tests covering search, filters, pagination, validation, and edge cases

##Testing

• API tests pass
• Type checking passes
• Lint passes
• Build passes
• Prettier checks pass for the Issue [Backend] Recruiter Talent Search #28 changes
• Manually tested the /api/talents endpoint with different filters and pagination scenarios

Closes #28

[Kaushik4141]

add your endpoints and payload in hoppscotch

[Kaushik4141]

Restrict the talents route to authorized recruiter and admin roles
So add requireAuth middleware and ensuring that the user is either a recruiter or a core_admin