Fix PCCC typed write encoding bugs caught by golden tests

- EncodeDataDescriptor passed the offset ref object instead of the
  offset number in the extended-type-id branch, so every typed write
  whose type id needs an extension byte (notably floats, id 0x08)
  threw ERR_INVALID_ARG_TYPE instead of writing
- TypedWriteRequest now rejects timer/counter/control/string/long
  addresses with a clear unsupported-type error; previously the
  undefined type id flowed into the descriptor encoder and produced
  the same cryptic TypeError
- PCCC internal replies no longer fall through to forward() when the
  context callback was already consumed

https://claude.ai/code/session_01AuAYuP6dTn8ALpkKErQuby

Author: claude

src/layers/pccc/encoding.js

@@ -65,7 +65,7 @@ export function EncodeDataDescriptor(data, offsetRef, id, size) {
   }
 
   if (idLength > 0 && sizeLength === 0) {
-    offsetRef.current = data.writeUInt8(((0b1000 | idLength) << 4) | size, offsetRef);
+    offsetRef.current = data.writeUInt8(((0b1000 | idLength) << 4) | size, offsetRef.current);
     offsetRef.current = encodeUnsignedInteger(data, offsetRef.current, id, idLength);
     return;
   }

src/layers/pccc/index.js

@@ -248,8 +248,10 @@ export default class PCCCLayer extends Layer {
       const callback = this.callbackForContext(savedContext.context);
       if (callback != null) {
         callback(getError(packet.status), packet, info);
-        return;
       }
+      /** internal replies must never be forwarded to upper layers,
+       * even if the callback was already consumed */
+      return;
     }
 
     this.forward(packet.data, info, savedContext.context);

src/layers/pccc/packet.js

@@ -229,6 +229,10 @@ export default class PCCCPacket {
       throw new Error(`Unsupported address: ${address}`);
     }
 
+    if (info.id == null) {
+      throw new Error(`Writing to ${info.datatype} files is not currently supported (address: ${address})`);
+    }
+
     const valueCount = values.length;
     const dataValueLength = valueCount * info.size;
     const dataTypeLength = DataTypeEncodingLength(info.id, info.size);