feat(host-agent): add workspace application entrypoint

apps/device-host-agent/host_agent/app.py

@@ -0,0 +1,15 @@
+from __future__ import annotations
+
+from dataclasses import dataclass
+
+
+@dataclass
+class HostAgentApplication:
+    """Process shell expanded by the Host Agent implementation tasks."""
+
+    def run(self) -> None:
+        return None
+
+
+def create_application() -> HostAgentApplication:
+    return HostAgentApplication()