Automatic Continuous Optical Scanner for Answer Sheets

Overview & Objective
Upgrade the Scan & Grade workflow from static photo-taking/file uploads to a continuous, real-time camera scanner. The system should automatically detect corner registration markers and decode the assessment QR code to grade answer sheets instantly without pressing a shutter button.

Live Camera Viewfinder Canvas:
- Display a continuous live video stream overlay with 4 green corner targeting reticles.
- Provide dynamic status indicators at the bottom (e.g., "Align squares in viewfinders", "Waiting on auto-focus", "Paper Found – Grading").
4-Point Corner Registration Tracking:
- Implement continuous edge/contour detection to lock onto the 4 solid black square markers printed at each corner of the official answer sheet.
- Compute real-time perspective homography and un-warp/rectify sheet skew upon 4-point alignment.
Top-Right QR Code Detection & Form Binding:
- Automatically decode the embedded QR code in the top-right corner on every valid frame.
- Extract assessment metadata (Course Code, Grading Period, Version/Form ID, and Item Count).
- Automatically load the corresponding answer key from the database without requiring manual dropdown selection by the instructor.
Continuous Auto-Grading Loop:
- Parse darkened OMR bubble rows (A, B, C, D) across student ID and question columns.
- Transition to a quick-review modal showing student details, total score, and item breakdown.
- After confirming or dismissing the modal, immediately cycle back to live viewfinder mode ready for the next paper.