docs: upgrade docus

[NyllRE]

🔗 Linked issue

resolves #730

❓ Type of change

• [-] 📖 Documentation (updates to the documentation or readme)
• [-] 🐞 Bug fix (a non-breaking change that fixes an issue)
• 👌 Enhancement (improving an existing functionality)
• ✨ New feature (a non-breaking change that adds functionality)
• [-] 🧹 Chore (updates to the build process or auxiliary tools and libraries)
• ⚠️ Breaking change (fix or feature that would cause existing functionality to change)

📚 Description

I've updated the main docus theme from @nuxt-themes/docus to the modern docus implementation and updated the pinia declaration.

Warning

On development there is a page not found error that doesn't affect the production build.

[netlify]

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Name	Link
🔨 Latest commit	5adb94c
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[NyllRE]

I assume this is how the app is supposed to look like as opposed to this.

[NyllRE]

@danielroe could you take a quick peek on this? Thanks

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 49.43%. Comparing base (c23a8b5) to head (5adb94c).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #762      +/-   ##
==========================================
- Coverage   55.05%   49.43%   -5.62%     
==========================================
  Files           4        4              
  Lines          89       89              
  Branches       29       29              
==========================================
- Hits           49       44       -5     
- Misses         40       44       +4     
- Partials        0        1       +1     

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