init API endpoint for generating labels

[MayNiklas]

Good evening!
I now finished cleaning up the API endpoint for generating labels feature I wrote about.

This time, I had some issues during development and used LLM's to fix those issues (I'm not really a PHP guy - this is my the first PHP project I'm working on in years). Therefore, please be extra careful in review!
If you don't like something, feel free to request changes or make them yourself (I allowed edits by maintainers).

I'm looking forward to receiving feedback.

I'm planning on using this feature by scripting a tool, that quickly requests labels and automatically prints them with my label printer. Maybe when scanning a LCSC bag with a scanner?

curl -X 'POST' \
  'http://localhost:9091/api/labels/generate' \
  -H 'accept: application/ld+json' \
  -H 'Content-Type: application/json' \
  -d '{
  "profileId": 1,
  "elementIds": "1,2,5-10",
  "elementType": "part"
}'

Greetings,
MayNiklas

[codecov]

Codecov Report

❌ Patch coverage is 78.94737% with 8 lines in your changes missing coverage. Please review.
✅ Project coverage is 54.77%. Comparing base (c2a51e5) to head (cfbe2f7).

Files with missing lines	Patch %	Lines
src/State/LabelGenerationProcessor.php	78.94%	8 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #1234      +/-   ##
============================================
+ Coverage     54.72%   54.77%   +0.04%     
- Complexity     7918     7929      +11     
============================================
  Files           596      597       +1     
  Lines         25468    25506      +38     
============================================
+ Hits          13937    13970      +33     
- Misses        11531    11536       +5     

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