perf(agent-runner): improve session registry and orchestrator efficiency

- Add pre-computed _authorized_ids (frozenset) at session registration for O(1) lookup
- Refactor is_resource_allowed() from linear search to set membership check
- Add thread-safe locking to get_session_registry() singleton
- Cache _session_registry and _state_store references in orchestrator __init__
- Add asyncio.gather() for parallel resource building in AgentResourceBuilder
- Create shared test fixtures in tests/unit_tests/agent/conftest.py
- Update test files to import from shared conftest.py

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

src/langbot/pkg/platform/sources/web_page_bot_adapter.py

@@ -84,6 +84,20 @@ class WebPageBotAdapter(abstract_platform_adapter.AbstractMessagePlatformAdapter
     ):
         self.listeners.pop(event_type, None)
 
+    async def is_stream_output_supported(self) -> bool:
+        """Delegate stream output check to ws_adapter."""
+        if self._ws_adapter is not None:
+            return await self._ws_adapter.is_stream_output_supported()
+        return False
+
+    async def create_message_card(
+        self, message_id: str | int, event: platform_events.MessageEvent
+    ) -> bool:
+        """Delegate create_message_card to ws_adapter."""
+        if self._ws_adapter is not None:
+            return await self._ws_adapter.create_message_card(message_id, event)
+        return False
+
     async def is_muted(self, group_id: int) -> bool:
         return False