[BE-45] Community feed: backend

[yusuftomilola]

Overview

A community bulletin board lets members post short updates, share opportunities, or celebrate milestones. Admins can pin important posts and moderate content. This is the backend for the FE-39 community feed.

Context

• User entity: backend/src/users/entities/user.entity.ts
• CommunityModule — may already exist for the directory endpoints (BE-11, BE-12); extend it here

Tasks

• Create CommunityPost entity: id, authorUserId (FK), body (text, max 1000 chars), isPinned (bool, default false), isDeleted (bool, default false), likeCount (int, default 0), createdAt, updatedAt
• Create CommunityPostLike entity: id, postId (FK), userId (FK), createdAt; unique constraint on (postId, userId)
• POST /community/posts — any active authenticated member creates a post; validate body max length
• GET /community/posts — paginated feed; pinned posts always first, then newest first; author basic info included
• DELETE /community/posts/:id — soft-delete own post (member) or any post (admin); sets isDeleted = true
• POST /community/posts/:id/like — toggle like: if already liked, unlike; if not liked, like; updates likeCount atomically
• PATCH /community/posts/:id/pin — toggle pin/unpin (admin only)

Files to Modify / Create

• New entities in backend/src/community/
• backend/src/community/community.controller.ts
• backend/src/community/community.module.ts