feat: add agent zones

backend/app/agent_zones/exceptions.py

@@ -0,0 +1,17 @@
+"""Agent Zone domain exceptions."""
+
+
+class AgentZoneError(Exception):
+    """Base Agent Zone error."""
+
+
+class AgentZoneNotFound(AgentZoneError):
+    """A Site or Agent Zone does not exist."""
+
+
+class AgentZoneValidationError(AgentZoneError):
+    """Agent Zone input or assignment is invalid."""
+
+
+class AgentZoneConflict(AgentZoneError):
+    """An Agent Zone uniqueness or assignment invariant conflicts."""