feat: add control board replacement workflow

backend/app/repairs/exceptions.py

@@ -107,3 +107,31 @@ class RepairActiveMismatch(RepairConflict):
 
 class RepairPersistenceError(RepairError):
     """Raised when a required repair persistence operation fails."""
+
+
+class ControlBoardReplacementActorRequired(RepairError):
+    """Raised when a board replacement lacks an authenticated actor."""
+
+    def __init__(self):
+        super().__init__("An authenticated actor is required to replace a control board")
+
+
+class ControlBoardReplacementConflict(RepairConflict):
+    """Raised when current repair, component, or MAC state blocks replacement."""
+
+
+class InvalidMacAddress(RepairError):
+    """Raised when a replacement MAC is malformed or prohibited."""
+
+    def __init__(self, message: str = "New MAC address is invalid"):
+        super().__init__(message)
+
+
+class MacOwnershipConflict(ControlBoardReplacementConflict):
+    """Raised when a MAC belongs to another durable miner."""
+
+    def __init__(self, normalized_mac: str):
+        self.normalized_mac = normalized_mac
+        super().__init__(
+            "MAC address has current or historical ownership on another miner"
+        )