[FEATURE] Add application status update notifications

[Pcmhacker-piro]

Description

After a student applies to a job through the one-click 'Apply with Profile' feature (#1207), there is no way to receive updates when the application status changes (e.g., when an employer reviews, accepts, or rejects the application). Students must manually check the application status or rely on external communication.

Steps to Reproduce

1. Apply to a job using the one-click apply feature
2. Wait for an employer to update the application status
3. Observe that there is no notification or alert when the status changes
4. The student must manually check the My Applications page to see updates

Expected Behavior

• Backend: When application status is updated (via admin/employer actions), create a notification for the student
• Backend: Add notification type 'application_status_update' to the Notification schema
• Frontend: Show notification in the bell dropdown when application status changes
• Frontend: Allow students to click on the notification to navigate to the My Applications page
• Frontend: Show different icons/colors for different status updates (accepted vs rejected)

Implementation Hints

Backend ( or wherever status updates occur):

• When updating application status, create a notification using the notification creation function
• Include relevant details: job title, company, old status, new status

Frontend:

• The notification system (Fix cheatsheets page not respecting theme mode #1097) should already handle displaying notifications
• May need to update the notification schema to include application_status_update type
• Ensure the notification includes a link to navigate to the specific application

Affected Files

• (if it exists, otherwise wherever status updates happen)
• (to add application_status_update type)
• (to handle the new type if needed)
• (if filtering is needed)

Labels

type:feature, level:intermediate, GSSoC-26