fix(s7): classic STRING/DT unrepresentable writes map to BadOutOfRange, not BadCommunicationError (#632)

S7.Net's own STRING/DT encoders throw ArgumentException; that fell into the
generic write catch (BadCommunicationError + Degraded health). Now surfaced as
S7ValueRangeException like the WSTRING/DATE codecs.

Claude-Session: https://claude.ai/code/session_01Ef2ozxS7QPanGT8uoATbTe

src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.S7/S7Driver.cs

@@ -1555,14 +1555,21 @@ public sealed class S7Driver
                 // ReadScalarBlockAsync read, so WriteBytesAsync writes the whole reserved STRING. A value
                 // longer than StringLength throws ArgumentException (S7.Net rejects overflow; we do NOT
                 // silently truncate). A null value encodes as the empty string.
-                return global::S7.Net.Types.S7String.ToByteArray(Convert.ToString(value) ?? "", tag.StringLength);
+                // #632: surfaced as S7ValueRangeException (→ BadOutOfRange) like the WSTRING codec — a
+                // client value error, not a comms fault (the raw ArgumentException used to land in the
+                // generic catch as BadCommunicationError + Degraded).
+                try { return global::S7.Net.Types.S7String.ToByteArray(Convert.ToString(value) ?? "", tag.StringLength); }
+                catch (ArgumentException ex) { throw new S7ValueRangeException($"S7 STRING value does not fit the declared {tag.StringLength}-character field: {ex.Message}"); }
 
             case S7DataType.DateTime:
                 // S7.Net's DateTime.ToByteArray builds the 8-byte DT BCD block. It validates the
                 // 1990–2089 DT range and throws ArgumentOutOfRangeException for an out-of-range year —
                 // we surface that (no silent clamp). Value coerced via Convert.ToDateTime (accepts a
                 // System.DateTime or a parseable timestamp string).
-                return global::S7.Net.Types.DateTime.ToByteArray(Convert.ToDateTime(value));
+                // #632: the range refusal maps to BadOutOfRange (see STRING above).
+                var dt = Convert.ToDateTime(value);
+                try { return global::S7.Net.Types.DateTime.ToByteArray(dt); }
+                catch (ArgumentOutOfRangeException ex) { throw new S7ValueRangeException($"S7 DATE_AND_TIME value {dt:O} is outside the DT range (1990–2089): {ex.Message}"); }
 
             // Writes refuse (S7ValueRangeException → BadOutOfRange) rather than truncate or clamp.
             case S7DataType.WString: return S7ValueCodecs.EncodeWString(value, tag.StringLength);