test: add Python directive drafter integration coverage

[rlippmann]

Summary

Add repo-owned deterministic Python coverage for the surviving directive-drafter integration variants and wire the real workspace dependency for test execution:

• LiteLLM with_directive_drafter
• LiteLLM Proxy context_compiler_precall_hook_with_directive_drafter
• Open WebUI open_webui_pipe_with_directive_drafter
• repo pyproject.toml + uv.lock so tests use the real context-compiler-directive-drafter package

Why

This gives context-compiler-example-integrations ownership of runnable directive-drafter integration coverage before deleting duplicate runnable integrations from context-compiler and context-compiler-directive-drafter.

Example metadata

• Enforcement point: Host-side request shaping and runtime decision handling around authoritative compiler state with optional directive drafting
• Domain: Example and reference integration coverage migration
• Technology/runtime: Python, pytest, LiteLLM, LiteLLM Proxy, Open WebUI
• Example type: reference integration / repository maintenance
• Does this use directive drafter? should normally be no: yes, intentionally for the optional variants covered here
• 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/test_litellm_with_directive_drafter.py python/tests/test_litellm_proxy_with_directive_drafter.py python/tests/test_openwebui_pipe_with_directive_drafter.py
• ./.venv/bin/pytest python/tests
• Result: 55 passed

The tests use the real workspace context-compiler and context-compiler-directive-drafter packages. Provider/model calls remain mocked.