feat(autogen): add native GovernanceInterventionHandler via AutoGen v0.4+ hooks (microsoft#1591)

Replace fragile monkey-patching with AutoGen's native intervention
handler system (DefaultInterventionHandler with on_send, on_publish,
on_response) introduced in AutoGen v0.4+.

Changes:
- Add GovernanceInterventionHandler class with three hooks:
  - on_send: tool call governance, content filtering, PII detection
  - on_publish: broadcast message governance
  - on_response: output content filtering, drift detection
- Add AutoGenKernel.as_handler() factory method as the recommended
  integration path
- Deprecate govern() and wrap() with DeprecationWarning pointing to
  as_handler()
- Export AutoGenGovernanceHandler from integrations package
- Add 51 new tests covering all three hook types, Cedar/OPA integration,
  deprecation warnings, PII detection, and backward compatibility
- All 18 existing AutoGen regression tests pass unchanged

Co-authored-by: Nishar <you@example.com>

Author: 2 people

agent-governance-python/agent-os/src/agent_os/integrations/__init__.py

@@ -60,7 +60,10 @@
 )
 from agent_os.integrations.a2a_adapter import A2AEvaluation, A2AGovernanceAdapter, A2APolicy
 from agent_os.integrations.anthropic_adapter import AnthropicKernel, GovernedAnthropicClient
-from agent_os.integrations.autogen_adapter import AutoGenKernel
+from agent_os.integrations.autogen_adapter import (
+    AutoGenKernel,
+    GovernanceInterventionHandler as AutoGenGovernanceHandler,
+)
 from agent_os.integrations.crewai_adapter import CrewAIKernel
 try:
     from agent_os.integrations.crewai_adapter import GovernanceHooks as CrewAIGovernanceHooks
@@ -173,6 +176,7 @@
     "CrewAIKernel",
     # AutoGen
     "AutoGenKernel",
+    "AutoGenGovernanceHandler",
     # OpenAI Assistants
     "OpenAIKernel",
     "GovernedAssistant",