fix(agent-runner): package context for plugin execution

src/langbot/pkg/agent/runner/__init__.py

@@ -12,6 +12,7 @@ from .errors import (
 )
 from .registry import AgentRunnerRegistry
 from .context_builder import AgentRunContextBuilder
+from .context_packager import AgentContextPackager
 from .resource_builder import AgentResourceBuilder
 from .result_normalizer import AgentResultNormalizer
 from .orchestrator import AgentRunOrchestrator
@@ -37,6 +38,7 @@ __all__ = [
     'RunnerExecutionError',
     'AgentRunnerRegistry',
     'AgentRunContextBuilder',
+    'AgentContextPackager',
     'AgentResourceBuilder',
     'AgentResultNormalizer',
     'AgentRunOrchestrator',