fix(driver-modbus-addressing): resolve Low code-review findings (Driver.Modbus.Addressing-006,007,009)

- Driver.Modbus.Addressing-006: broaden the catch in TryParseFamilyNative
  so a future helper throwing a non-Argument/Overflow type still satisfies
  the try-parse contract.
- Driver.Modbus.Addressing-007: document that the address grammar does
  not carry ModbusStringByteOrder (the structured-tag path does);
  add a 'Grammar scope' bullet to docs/v2/dl205.md.
- Driver.Modbus.Addressing-009: reword the ModbusModiconAddress comments
  so they don't imply a leading-digit invariant the parser doesn't
  enforce.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Modbus.Addressing/ModbusModiconAddress.cs

@@ -52,10 +52,14 @@ public static class ModbusModiconAddress
             return false;
         }
 
-        // Range check up-front — keeps the rest of the parser straight-line. 5-digit Modicon
-        // is always exactly 5 chars (40001..49999, with the lead digit selecting region), and
-        // 6-digit is exactly 6 (400001..465536-shaped). Anything else is unambiguously
-        // malformed so we reject before doing the per-character work.
+        // Range check up-front — keeps the rest of the parser straight-line. Modicon addresses
+        // are exactly 5 or 6 characters: a leading region digit (0/1/3/4 — coils, discrete
+        // inputs, input registers, holding registers respectively) followed by 4 (5-digit form)
+        // or 5 (6-digit form) trailing digits encoding the 1-based register number. The
+        // 5-digit form covers 1..9999 per region (e.g. coils 00001..09999, holding registers
+        // 40001..49999); the 6-digit form covers the full 1..65536 wire range (e.g. coils
+        // 000001..065536, holding 400001..465536). Anything else is unambiguously malformed so
+        // we reject before doing the per-character work.
         var s = address.Trim();
         if (s.Length is not (5 or 6))
         {
@@ -100,9 +104,10 @@ public static class ModbusModiconAddress
             return false;
         }
 
-        // 5-digit form caps at 9999 by construction (4 trailing digits); reject if the parsed
-        // value exceeds the wire-protocol maximum of 65536 (i.e. PDU offset 65535). 6-digit
-        // form can address the full 65535-offset range.
+        // Wire-protocol maximum is register number 65536 (PDU offset 65535). The 5-digit form's
+        // 4 trailing digits can only encode up to 9999, so this check is reached only by the
+        // 6-digit form in practice — but it is applied to both for safety / simplicity rather
+        // than relying on the digit-count invariant.
         if (registerNumber > 65536)
         {
             error = $"Modicon register number {registerNumber} exceeds the wire maximum (65536 / PDU offset 65535)";