improvement(frontend): add pageNum URL parameter

add visualization for the number of contest entrants

refactor to improve backend code clarity

add FFT implementation

last version prior to the rewrite of the Elo rating algorithm

refine backend logic to enhance robustness and clean up deprecated st…

…atic site rendering code

refactor(front-end): using React.js to build front-end

first version in production at 11/14/2022

initial version: to make this repo public