feat(themes): add milkyway theme (@NeraShi)

[NeraShi]

Description

Created for comfortable night typing sessions, inspired by the calm of midnight skies.

Preview

Colorful mode = false, flip colors = false

Colorful mode = false, flip colors = true

Colorful mode = true, flip colors = false

Colorful mode = true, flip colors = true

Results example

Checks

• Adding a theme?
  • Make sure to follow the themes documentation
  • Add theme to packages/schemas/src/themes.ts
  • Add theme to frontend/src/ts/constants/themes.ts
  • Add theme css file to frontend/static/themes
  • Add some screenshot of the theme, especially with different test settings (colorful, flip colors) to your pull request
• Check if any open issues are related to this PR; if so, be sure to tag them below.
• Make sure the PR title follows the Conventional Commits standard. (https://www.conventionalcommits.org for more info)
• Make sure to include your GitHub username prefixed with @ inside parentheses at the end of the PR title.

[thesomewhatyou]

feels a bit like trance honestly

just less pink

[Miodec]

Sorry, its too simmilar to already available themes.