Update README & CodeCov Setup

[PSchmiedmayer]

Update README & CodeCov Setup

♻️ Current situation & Problem

• The README provides little visual information to understand the project

⚙️ Release Notes

• Adds badges to the README
• Adds a TestFlight download link to the README
• Fixes the CodeCov Setup

📚 Documentation

• Improves the README

✅ Testing

• No code changes, does not require any tests

📝 Code of Conduct & Contributing Guidelines

By submitting creating this pull request, you agree to follow our Code of Conduct and Contributing Guidelines:

• I agree to follow the Code of Conduct and Contributing Guidelines.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (365126e) 31.56% compared to head (a030172) 31.56%.

Additional details and impacted files

@@           Coverage Diff           @@
##             main       #7   +/-   ##
=======================================
  Coverage   31.56%   31.56%           
=======================================
  Files          31       31           
  Lines         976      976           
=======================================
  Hits          308      308           
  Misses        668      668           

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