Add landing page

[pokey]

Checklist

• [ ] Record and add "What is Cursorless?" video
• [ ] Fix white side bars on horizontal mobile layout
• [ ] Fix my desktop layout
• [ ] Fix iPad horizontal layout (video should be vertically centred?)
• [ ] Tweak hover colors
• [ ] Add cheatsheet to website
• [ ] Link to cheatsheet from docs?
• [ ] Change web version of cheatsheet to look different somehow
• [ ] Add instructions for updating cheatsheet json
• [ ] Add title
• [ ] Add SEO / social header stuff
• [ ] Add favicon
• [ ] Add arrow to indicate to scroll down / make it so clicking anywhere scrolls down
• [x] Support playing video full screen
• [x] Center logo within its svg by tweaking viewport
• [x] Support light player
• [x] Check horizontal mobile layout
• [x] Use YouTube cookie-free
• [x] Use css to set body bg color and remove helmet; it's too slow
• [x] Figure out why styling was lost on docs site; prob want to avoid tailwind outside landing page

[netlify[bot]]

✅ Deploy Preview for cursorless ready!

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[pokey]

Remove unnecessary .gitkeep