feat: integrate AgentSpeak with semantic belief extraction

ref: N25B-429

src/control_backend/schemas/belief_list.py

@@ -0,0 +1,14 @@
+from pydantic import BaseModel
+
+from control_backend.schemas.program import Belief as ProgramBelief
+
+
+class BeliefList(BaseModel):
+    """
+    Represents a list of beliefs, separated from a program. Useful in agents which need to
+    communicate beliefs.
+
+    :ivar: beliefs: The list of beliefs.
+    """
+
+    beliefs: list[ProgramBelief]