feat(adagents): add permissive property resolver

[sangilish]

Summary

Refs #711.

This adds an explicit opt-in resolver for operational adagents.json files that list a sales agent in authorized_agents[] but omit the schema-conformant authorization_type selector.

The existing get_properties_by_agent() behavior stays strict and unchanged. New callers can use:

resolve_properties_for_agent(adagents_data, agent_url, mode="permissive")

In permissive mode, a matching bare authorized_agents entry resolves to the file's top-level properties[]. The fallback only applies when the entry has no authorization_type and no known selector field. If the agent is not listed, or if the entry has an explicit selector, the result remains the strict result.

What changed

• Added resolve_properties_for_agent(..., mode="strict" | "permissive").
• Kept get_properties_by_agent() as the strict path.
• Exported the new helper from adcp.__all__ and updated the public API snapshot.
• Added tests covering:
  • default strict behavior for bare entries remains empty
  • permissive bare-entry fallback returns top-level properties
  • permissive mode still requires the agent URL to be listed
  • permissive mode does not override broken explicit selectors
  • revoked publisher domains are excluded from fallback results
  • unknown modes fail loudly

Testing

• uv run pytest tests/test_adagents.py -q -k "resolve_properties_for_agent or get_properties_by_agent"
• uv run pytest tests/test_public_api.py tests/test_adagents.py -q
• uv run pytest -q
• uv run ruff check src/adcp/adagents.py src/adcp/__init__.py tests/test_adagents.py tests/fixtures/public_api_snapshot.json
• uv run mypy src/adcp
• git diff --check

Note: uv run ruff check across the full repository currently reports pre-existing lint drift in unrelated tests. The files touched in this PR pass ruff.