fix: remove phantom deps from requirements.txt and correct stale README content

[Copilot]

Summary

requirements.txt listed 6 packages that are never imported (dlib, face-recognition, face-recognition-models, cmake, openpyxl, click). The project ships its own src/face_recognition.py (OpenCV Haar + HOG, no dlib), making those entries misleading and install-breaking. README had corresponding stale content.

Type of Change

• Bug fix
• New feature
• Refactor / code quality
• Documentation update
• Other: Dependency cleanup

Changes Made

requirements.txt — stripped to only what is actually imported:

• Removed: cmake, dlib>=19.7, face-recognition>=1.3.0, face-recognition-models, openpyxl==3.1.2, click
• Kept: opencv-python, numpy, Pillow, pandas, flask

README.md — corrected five stale sections:

• Quick Start: pip install flask → pip install -r requirements.txt
• Installation: removed "dlib may take 5–10 min" note
• How It Works: "SIFT features" → "HOG-based gradient features" (matches src/face_recognition.py)
• Troubleshooting: replaced pip install face-recognition with accurate note that the project uses a local mock module
• Project structure + Dependencies: added basic_face_recognition.py and images/Basic/; dependency table now reflects actual requirements.txt

Testing

• Existing tests pass (pytest tests/ -v)
• New tests added for new functionality
• Manually tested with webcam

Checklist

• Code follows the project style (PEP 8, max line length 120)
• README updated if behaviour changed
• CHANGELOG.md updated under [Unreleased]