Add a "Project description" section to clarify the purpose of the sudoku generator research project, and correct inconsistent markdown heading levels (changing from `####` to `##` or `###`) for screenshots and solver subsections to improve document structure and readability.
The readme now includes the exact number of valid Sudoku puzzles (6.67 × 10²¹) and explicitly states the project's focus on generating and solving the hardest possible sudokus, replacing the vague reference to backtracking algorithms.
Add Makefile with build targets for sudoku solver, generator, and coverage reporting.
Include NOTES.md explaining sudoku difficulty factors and solving techniques.
Add README.md with puzzle examples and generator output.
Implement app.js with Grid and Grid2 classes for rendering puzzle data in the browser.
Add box.c with functions for box indexing, grid-to-array conversion, and box value extraction.
Include footer.h with terminal size detection, cursor positioning, and footer display utilities.
Add index.html with CSS grid layout and script loading for the web interface.
Include rlib.h as a large utility header library.
