feat: Offline Mode for Face Recognition (#3872)

[anshika1179]

Description

This PR addresses issue #3872 by implementing a robust Offline Mode for the Face Recognition Attendance System.

• It locally caches student descriptor profiles (labels) directly onto the teacher's device via IndexedDB (offlineStore.js), allowing the recognition engine to securely identify students even without network connectivity.
• The AI models themselves continue to be efficiently pre-loaded and offloaded utilizing Web Workers, preventing main-thread UI freezing.
• When offline, attendance logs are securely queued locally and then automatically pushed and resolved against the server once the network is restored.

Fixes #3872

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• My changes generate no new warnings