[ImgBot] Optimize images

*Total -- 6,704.13kb -> 5,733.26kb (14.48%)

/img/banner-large.png -- 843.95kb -> 587.27kb (30.41%)
/img/banner.png -- 923.32kb -> 649.52kb (29.65%)
/img/logo-nobg.png -- 484.11kb -> 389.89kb (19.46%)
/frontend/public/logo.png -- 484.11kb -> 389.89kb (19.46%)
/img/logo.png -- 858.35kb -> 720.94kb (16.01%)
/img/logo-small.jpg -- 18.87kb -> 16.63kb (11.87%)
/frontend/public/flags/jp.svg -- 0.46kb -> 0.42kb (8.72%)
/frontend/public/flags/it.svg -- 0.28kb -> 0.26kb (7.96%)
/frontend/public/flags/de.svg -- 0.22kb -> 0.21kb (4.98%)
/frontend/public/flags/fr.svg -- 0.23kb -> 0.21kb (4.76%)
/frontend/public/flags/cn.svg -- 0.79kb -> 0.76kb (3.81%)
/frontend/public/infographic.png -- 2,653.60kb -> 2,552.61kb (3.81%)
/frontend/public/flags/gb.svg -- 0.49kb -> 0.48kb (3.37%)
/frontend/public/Flashy_flashe.png -- 355.58kb -> 346.00kb (2.7%)
/frontend/public/flags/es.svg -- 79.76kb -> 78.17kb (1.99%)

Signed-off-by: ImgBotApp <ImgBotHelp@gmail.com>

Author: ImgBotApp