fix: include additionalProperties in schema traversal for model_rebuild

[hsunner]

_get_combined_attributes omitted additionalProperties, so inline schemas used as map value types (e.g. nullable+allOf+$ref) were never registered in the types dict and never had model_rebuild called. This left generated Pydantic models with unresolved ForwardRefs (pydantic_complete=False).

Fixes the case:
additionalProperties:
nullable: true
allOf:
- $ref: '#/components/schemas/SomeModel'

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 93.90%. Comparing base (068bd58) to head (ce6e008).

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #438      +/-   ##
==========================================
+ Coverage   93.89%   93.90%   +0.01%     
==========================================
  Files         104      104              
  Lines        8397     8414      +17     
==========================================
+ Hits         7884     7901      +17     
  Misses        513      513              

Flag	Coverage Δ
core	93.90% <100.00%> (+0.01%)	⬆️
extras	93.90% <100.00%> (+0.01%)	⬆️

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[hsunner]

I can produce a test for this too, but copilot placed the reference schema in tests/fixtures, and by the README.md I'm not sure this is a good idea. I will push it to the branch as a new commit

(Sorry for ghosting you when I last worked with this codebase; I got pulled to something else after that summer. Should have replied once I realised I had left you hanging)

[commonism]

Hi,

types with multiple identities (here: object|null) have to be RootModels, else there is inconsistent behavior.
Here - when specifying the type of the additionalPropert as "object" it will enforce a RootModel.

This changes the access to the model - using .root on the model.

I added the missing bits to make this happen.

Don't worry about the PR interaction in 2023, to me everything was fine.

[hsunner]

Awesome, thank you!