API: Implement Board CRUD endpoints

[lucianfialho]

Problem

Currently the platform has no API endpoints for creating, reading, updating, or deleting Boards. These are foundational CRUD operations needed for the pivot to curated collections.

Solution

Implement RESTful Board management endpoints.

Acceptance Criteria

• POST /api/boards - Create new board

  • Request body: { title, description?, isPublic? }
  • Response: { id, ownerId, createdAt, ... }
  • Requires authentication
  • Returns 401 if not authenticated

• GET /api/boards - List user's boards

  • Query params: owned=true|false, limit=20, offset=0
  • Response: { boards: Board[], total: number }
  • Includes owned + collaborated boards

• GET /api/boards/[id] - Get single board

  • Response: Board with papers array + members array
  • Returns 404 if not found
  • Returns 403 if user is not a member

• PATCH /api/boards/[id] - Update board

  • Request body: { title?, description?, isPublic? }
  • Requires owner role
  • Returns 403 if not owner

• DELETE /api/boards/[id] - Delete board

  • Requires owner role
  • Cascades to board_papers and board_members
  • Returns 403 if not owner

Dependencies

• Issue Data Model: Design and implement Board entity and schema #1: Data Model schema must be created first

Notes

• All endpoints should validate authentication via auth() helper
• Use Drizzle ORM for queries
• Follow existing error handling patterns in the codebase