test: add Python example integration coverage

[rlippmann]

Summary

Add repo-owned deterministic Python coverage for the moved example and reference integration slices:

• LiteLLM prompt-construction example and local confirmation helper behavior
• schema-selection examples for LiteLLM response_format and Ollama structured output
• reference integrations for LiteLLM Proxy and Open WebUI Pipe

Why

This prepares context-compiler-example-integrations to own its Python example coverage so copied tests can be removed from context-compiler without losing deterministic checks for example behavior.

Example metadata

• Enforcement point: Host-side request shaping and runtime decision handling around Context Compiler state
• Domain: Example and reference integration coverage migration
• Technology/runtime: Python, pytest, LiteLLM reference integration, Open WebUI reference integration
• Example type: reference integration / repository maintenance
• Does this use directive drafter? should normally be no: no
• Does this derive state from model output? must be no for primary examples: no

Checklist

• Repository scaffolding / governance change
• One primary enforcement point
• Explicit authoritative state
• No model-derived state mutation
• Adversarial stub or equivalent test
• Observable runtime behavior change
• Domain vocabulary is natural
• Framework is secondary to the enforcement point
• Docs updated
• Tests/smoke checks added where practical

Notes

Validation run:

• ./.venv/bin/pytest python/tests
• Result: 42 passed

Scope intentionally excludes core engine conformance coverage and preprocessor/directive-drafter-specific reference integration tests in this slice.