Fix long name clamping and adjust related structures for compatibility

src/meshUtils.h

@@ -60,6 +60,17 @@ size_t pb_string_length(const char *str, size_t max_len);
 // Ensures the result is null-terminated within bufSize. Returns true if any bytes were replaced.
 bool sanitizeUtf8(char *buf, size_t bufSize);
 
+// Longest User.long_name content (bytes, excluding NUL) we store or transmit.
+// The wire decode buffer stays at 40 so names from senders built against the
+// older 39-byte limit still parse; everything we keep or send is clamped to
+// this, matching the slim NodeInfoLite storage width in deviceonly.proto.
+#define MAX_LONG_NAME_BYTES 24
+
+// Clamp a long_name buffer (at least MAX_LONG_NAME_BYTES + 1 bytes) in-place
+// to MAX_LONG_NAME_BYTES bytes of content, fixing any partial UTF-8 sequence
+// left at the cut.
+void clampLongName(char *longName);
+
 /// Calculate 2^n without calling pow() - used for spreading factor and other calculations
 inline uint32_t pow_of_2(uint32_t n)
 {