Foundation for the Modbus addressing-grammar work tracked in #137-#145. Adds
ModbusModiconAddress.Parse / TryParse that turns classic Modicon strings
(40001 / 400001 / 30001 / 00001 / 10001) into (Region, ushort PduOffset).
Also extracts ModbusRegion to a new Driver.Modbus.Addressing assembly so the
Admin UI (#145) can reference the addressing surface without taking a dep on
the wire driver. The new assembly intentionally extends the same
ZB.MOM.WW.OtOpcUa.Driver.Modbus namespace as the driver — callers see the
type as if it lived in one place; only the project layout changes. No
existing call site needed editing (zero-churn move).
Behaviour:
- Single leading digit selects region (0=Coils, 1=DiscreteInputs,
3=InputRegisters, 4=HoldingRegisters).
- 5-digit form: trailing 4 digits are 1-based register, supports 1..9999.
- 6-digit form: trailing 5 digits are 1-based register, supports 1..65536
(full PDU address space).
- Strict 5-or-6 length check; whitespace trimmed; clear FormatException
diagnostics for every malformed shape (wrong length, non-digit body,
illegal leading digit, register zero, register overflow).
29/29 new unit tests pass. Full Driver.Modbus suite (182 tests) and the
solution-wide build still green after the ModbusRegion move.
501d8f494b