Create searchable climate projects REST API

Build a Next.js API route that lets developers search and filter the climate tech project database.

GET /api/climate-projects?q=&category=&language=&minStars=&needsContributors=&limit=20&cursor=

Database table climate_projects:

id uuid PK, name text, description text, repo_url text,
category text, primary_language text, stars integer,
has_good_first_issues boolean, last_commit_at timestamptz,
created_at timestamptz

Query behavior:

1. Full-text search on name and description using PostgreSQL to_tsvector('english', name || ' ' || description) — add a GIN index
2. Filter by category (exact match), primary_language (exact match), minStars (>=), needsContributors (maps to has_good_first_issues = true)
3. Sort: by text rank if q is provided, otherwise stars DESC
4. Cursor-based pagination: cursor is an opaque base64-encoded {id, stars} pair
5. Response: { projects: Project[], total: number, nextCursor: string | null }

Validate all query params with zod. Return 400 with descriptive error on invalid params.

Include the Drizzle migration for the climate_projects table with proper indexes.