feat(gatekeeper): implement end-to-end verification pipeline (Resolves #9)

[amankoli09]

Closes #23

Overview

This PR introduces the complete end-to-end examination verification pipeline for the GATEKEEPER module, integrating all necessary verification stages into a unified flow.

Changes Made

• Integrated Verification Stages: Connected Roll Number Verification, Face Verification, Student Registry Lookup, Face History Check, and Identity Conflict Detection into a sequential pipeline (gatekeeper_pipeline.py).
• Authorization Engine: Implemented the final authorization engine to evaluate results from all stages and generate deterministic examination access decisions.
• Frontend Adjustments: Removed the Spline logo from the frontend application and refined UI styling.
• Cleaned Up Dependencies: Removed accidentally tracked node_modules from the repository to ensure a clean commit history.

Verification

• Verified students successfully pass through the pipeline and receive access.
• Unauthorized or conflicting identities are properly detected and blocked.
• The pipeline executes deterministically and provides structured reasoning for its final decision.