feat: implement VAD agent

Listens to audio from the RI, does voice activity detection, sends voice fragments.

ref: N25B-213

src/control_backend/main.py

@@ -13,6 +13,7 @@ import zmq
 
 # Internal imports
 from control_backend.agents.bdi.bdi_core import BDICoreAgent
+from control_backend.agents.vad_agent import VADAgent
 from control_backend.api.v1.router import api_router
 from control_backend.core.config import AgentSettings, settings
 from control_backend.core.zmq_context import context
@@ -34,6 +35,9 @@ async def lifespan(app: FastAPI):
     # Initiate agents
     bdi_core = BDICoreAgent(settings.agent_settings.bdi_core_agent_name + '@' + settings.agent_settings.host, settings.agent_settings.bdi_core_agent_name, "src/control_backend/agents/bdi/rules.asl")
     await bdi_core.start()
+
+    _temp_vad_agent = VADAgent("tcp://localhost:5558", False)
+    await _temp_vad_agent.start()
     
     yield