Function announcement_routes

pub fn announcement_routes(app_state: AppState) -> Router<AppState>

Builds the /announcements route group for a specific module.

Routes:

• POST / → create announcement (lecturer or assistant lecturer only)
• GET / → list announcements
• GET /{announcement_id} → get single announcement (with author id & username)
• PUT /{announcement_id} → edit announcement (lecturer or assistant lecturer only)
• DELETE /{announcement_id} → delete announcement (lecturer or assistant lecturer only)