Fix(Finding_Lanes): Dynamic ROI, slope filtering, multi-source CLI, visualizer, unit tests & docs (#467)

[Prayas340]

Description

Fixes #467

This PR resolves multiple critical bugs, edge cases, and architectural limitations in Finding_Lanes:

1. Dynamic ROI Polygon Masking: Replaced static pixel coordinates with dynamically scaled polygon vertices proportional to frame width and height, preventing distortion and out-of-bounds errors on arbitrary video and image resolutions.
2. Color Space Standardization: Fixed Canny edge preprocessing to correctly convert OpenCV BGR frames via cv2.COLOR_BGR2GRAY.
3. Slope-Intercept Noise Filtering & Coordinate Safety: Added min_slope filtering (default 0.3) in average_lines_intercept to ignore near-horizontal road markings and shadows. Added zero-division, NaN, and infinity safeguards in make_coordinate to prevent crashes and int conversion overflow.
4. Multi-Source CLI Engine: Added CLI argument parsing (--image, --video, --camera, --output, --no-show) to process static images, pre-recorded video files, or live webcam streams, with optional output saving for headless / CI workflows.
5. Multi-Stage Pipeline Visualizer (sub.py): Enhanced sub.py into a 4-stage visualizer (Original RGB, Canny Edges, Dynamic ROI, and Hough Lane Overlay) using Matplotlib subplots for diagnostics and educational demonstration.
6. Comprehensive Unit Test Suite (test_lanes.py): Added 14 unit tests covering edge detection, ROI masking, coordinate generation, slope filtering, error handling, intermediate dictionary extraction, and end-to-end frame processing (100% pass rate).
7. Standardized Documentation (README.md): Restructured documentation following README_TEMPLATE.md, including pipeline breakdown, installation instructions, full CLI reference, test commands, and project hierarchy.

• Issue_no: [Finding_Lanes] Fix ROI hardcoding, color space mismatch, line slope filtering, and add CLI & unit tests #467

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Documentation Update

Project

• Your Project Name: Finding Lanes

• Short Description: Computer vision road lane detection pipeline using OpenCV, NumPy, dynamic ROI masking, Hough line transform, and linear regression averaging.

Checklist:

• I have named my files and folder, according to this project's guidelines.
• My code follows the style guidelines of this project.
• I have commented on my code, particularly in hard-to-understand areas.
• I have created a helpful and easy to understand README.md, according to the given README_TEMPLATE.md.
• My changes do not produce any warnings.
• Added unit tests in test_lanes.py (14/14 passed).

[Prayas340]

?? Automated Testing & Verification Summary

All core functions and edge cases have been tested and verified:

`
test_average_lines_detection ......................... ok
test_average_lines_intercept_none_and_empty .......... ok
test_average_lines_slope_filtering ................... ok
test_canny_edge_detection ............................ ok
test_canny_grayscale_input ........................... ok
test_display_lines ................................... ok
test_display_lines_none .............................. ok
test_dynamic_roi_masking ............................. ok
test_make_coordinate_edge_cases ...................... ok
test_make_coordinate_valid ........................... ok
test_process_bundled_image_if_present ................ ok
test_process_frame_end_to_end ........................ ok
test_process_frame_intermediates ..................... ok
test_roi_custom_polygon .............................. ok

Ran 14 tests in 0.179s - OK
`

• Video Stream Validation: Processed all 213 frames in video.mp4 with zero dropped frames or exceptions.
• Static Image Validation: Processed picture.jpg with both left and right lane lines correctly extracted.
• Headless & CLI Output: Tested --no-show and --output parameter handling.