Set confidence threshold to 80% and remove slider from frontend

✅ Frontend Changes:
- Removed confidence threshold slider from web interface
- Added fixed 80% confidence display with green info box
- Updated JavaScript to use fixed 0.8 threshold
- Removed slider-related CSS styles

✅ Backend Changes:
- Updated all API endpoints to default to 80% confidence (0.8)
- Modified POST /detect, GET /detect/hardcoded, POST /detect/base64
- Updated comments to reflect new default threshold

✅ Testing Updates:
- Updated test_api.py to use 80% confidence for all tests
- Ensures consistent testing with new threshold

✅ Benefits:
- High precision mode (80% confidence) reduces false positives
- Simplified user interface without threshold adjustment
- Consistent detection behavior across all endpoints

requirements.txt

@@ -8,6 +8,7 @@ Pillow==10.0.1
 # Web Framework
 Flask==2.3.3
 Flask-CORS==4.0.0
+Flask-RESTX==1.3.0
 Werkzeug==2.3.7
 
 # Data Processing