[ImgBot] Optimize images

*Total -- 715.59kb -> 392.90kb (45.09%)

/public/grain.png -- 189.40kb -> 61.04kb (67.77%)
/public/rays.png -- 505.45kb -> 312.38kb (38.2%)
/public/tools/turborepo.png -- 20.74kb -> 19.49kb (6.06%)

Signed-off-by: ImgBotApp <[email protected]>

Author: ImgBotApp