feat(tests): overhaul staging test infrastructure and update fixtures

[tychtjan]

Summary

Added staging test support (PYTHON_DEX), which required rewrites in the test
infrastructure (dynamic PostgreSQL URL replacement instead of duplicating fixtures)
and a new CI workflow for pre-merge staging tests.

Changes by commit

1. chore: regenerate API client from updated OpenAPI spec

• Updated OpenAPI-generated API client with new models and endpoints
• Reviewer: auto-generated, safe to skip

2. feat(ci): add staging test infrastructure and harden test setup

• Add staging-tests.yaml workflow (triggered by label, /test-staging comment, or manual dispatch)
• Overhaul conftest.py for dynamic data source URL replacement (staging vs local)
• Add clean_staging.py and upload_demo_layout.py helper scripts
• Unify token passing: all staging make targets use TOKEN= argument
• Fix LLM provider patch to use InAttributes after spec removed PatchAttributes
• Add alternativeDataSourceId to data source fixture
• Document staging test workflow in CONTRIBUTING.md

3. chore: regenerate test cassettes

• Regenerated all cassettes against staging environment
• Reviewer: regenerated fixtures, safe to skim

Test plan

• Passes local tests
• Passes staging environment tests

JIRA: DX-431
risk: low

[codecov]

Codecov Report

❌ Patch coverage is 50.00000% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 77.24%. Comparing base (e650ab3) to head (5bc7b49).

Files with missing lines	Patch %	Lines
.../catalog/organization/entity_model/llm_provider.py	50.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1392      +/-   ##
==========================================
- Coverage   77.36%   77.24%   -0.12%     
==========================================
  Files         228      227       -1     
  Lines       14775    14672     -103     
==========================================
- Hits        11430    11334      -96     
+ Misses       3345     3338       -7     

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[tychtjan]

I analyzed why there were some of the bigger deletes in the fixtures

 # OLD: cleanup + verification assertion
  finally:
      sdk.catalog_organization.delete_jwk("demoJwk")
      assert len(sdk.catalog_organization.list_jwks()) == 0  # <-- this GET is now gone

The new pattern uses safe_delete() which only calls the delete, no verification list:

  # NEW: cleanup only, no verification
  finally:
      safe_delete(sdk.catalog_organization.delete_jwk, "demoJwk")

This removes the final GET ...?page=0&size=500 call that verified the entity was gone.
That's why every cassette has a trailing interaction block removed — it was the VCR recording of
that verification GET. This is entirely expected and correct. The verification was fragile on staging (where other entities may exist, making len(...) == 0 fail), and the safe_delete + snapshot/restore approach is more robust.