Shared fault-detection: threshold + status-bit + fault-code enum

[mfaferek93]

A reusable fault-detection module so any value source maps raw values to faults the same way, matching how supervisory systems read device faults.

• Detection modes per mapped point, composable in the node-map: numeric threshold (above/below), status-word bit decode (named bit -> fault), fault-code value enum mapping (code -> fault code + text).
• One evaluator: given a value + the point's detection config, decide raise/clear + fault code/severity/text. Reused by the OPC UA plugin and other protocol plugins.
• Migrate the OPC UA plugin's existing threshold logic onto this evaluator so it gains bit-decode + enum for free.
• Acceptance: a status-word bit and a fault-code enum each raise a fault with the mapped code/text from the shared evaluator; numeric threshold still works; unit-tested.