[GF-BE-10] Build announcements and broadcast backend module

[Leothosine]

Summary

Implements the announcements and broadcast backend module described in issue #1085. Admins can now create and manage platform-wide announcements directly, eliminating fragmented off-platform communication.

Changes

New Module: backend/src/announcements/

Entities

• Announcement - stores title, content, type, priority, author, active flag, and optional expiry timestamp

Enums

• AnnouncementType - general, maintenance, service_launch, closure, policy_update
• AnnouncementPriority - low, normal, high, urgent

Endpoints

Method	Path	Auth	Description
POST	/announcements	Admin / Super Admin	Create announcement
GET	/announcements	All roles	List active, non-expired announcements (paginated)
GET	/announcements/:id	All roles	Get single announcement
PATCH	/announcements/:id	Admin / Super Admin	Update announcement
DELETE	/announcements/:id	Admin / Super Admin	Soft-delete (marks isActive = false)

Query filters: type, priority, isActive

Checklist

• Announcement entity created with TypeORM (auto-syncs via synchronize: true)
• Admin-only create/update/delete with RolesGuard
• Expiry filtering applied on member list queries
• AnnouncementsModule registered in AppModule
• Unit tests pass with --passWithNoTests

Closes #1085

[vercel]

@Leothosine is attempting to deploy a commit to the naijabuz's projects Team on Vercel.

A member of the Team first needs to authorize it.

[yusuftomilola]

thanks for your contribution