feat(font): add 0xProto font (@0x7375) (#6750)

### Description

- added [0xProto](https://github.com/0xType/0xProto) font file to
webfonts
- updated `frontend/static/{fonts/_list.json,styles/fonts.scss}` files
- tried it locally, here's a screenshot:
<img width="1920" height="1080" alt="Screenshot-18-07-2025-0414"
src="https://github.com/user-attachments/assets/597837b0-ce8c-4a32-8e08-52ded6c01901"
/>


### Checks

- [ ] Adding quotes?
- [ ] Make sure to include translations for the quotes in the
description (or another comment) so we can verify their content.
- [ ] Adding a language?
- Make sure to follow the [languages
documentation](https://github.com/monkeytypegame/monkeytype/blob/master/docs/LANGUAGES.md)
  - [ ] Add language to `packages/contracts/src/schemas/languages.ts`
- [ ] Add language to exactly one group in
`frontend/src/ts/constants/languages.ts`
  - [ ] Add language json file to `frontend/static/languages` 
- [ ] Adding a theme?
- Make sure to follow the [themes
documentation](https://github.com/monkeytypegame/monkeytype/blob/master/docs/THEMES.md)
  - [ ] Add theme to `packages/contracts/src/schemas/themes.ts`
  - [ ] Add theme to `frontend/src/ts/constants/themes.ts`
  - [ ] Add theme css file to `frontend/static/themes`
- Also please add a screenshot of the theme, it would be extra awesome
if you do so!
- [ ] Adding a layout?
- [ ] Make sure to follow the [layouts
documentation](https://github.com/monkeytypegame/monkeytype/blob/master/docs/LAYOUTS.md)
  - [ ] Add layout to `packages/contracts/src/schemas/layouts.ts`
  - [ ] Add layout json file to `frontend/static/layouts` 
- [ ] Check if any open issues are related to this PR; if so, be sure to
tag them below.
- [x] Make sure the PR title follows the Conventional Commits standard.
(https://www.conventionalcommits.org for more info)
- [x] Make sure to include your GitHub username prefixed with @ inside
parentheses at the end of the PR title.

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Author: 0x7375

frontend/src/styles/fonts.scss

@@ -110,6 +110,9 @@ $fonts: (
   "Iosevka": (
     "src": "Iosevka-Regular",
   ),
+  "0xProto": (
+    "src": "0xProto-Regular",
+  ),
 );
 
 $font-defauls: (

frontend/static/fonts/_list.json

@@ -117,5 +117,8 @@
   },
   {
     "name": "Iosevka"
+  },
+  {
+    "name": "0xProto"
   }
 ]