Optimize FastReader.readUntil() scan loop and simplify position update

Use do-while with single array access per iteration instead of double
access in while condition. Hoist position assignment above delimiter
check to eliminate duplicate write.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: jdereg

src/main/java/com/cedarsoftware/util/FastReader.java

@@ -225,21 +225,20 @@ public int readUntil(final char[] dest, int off, int maxLen, char delim1, char d
             int pos = position;
             int end = pos + Math.min(limit - pos, maxLen - totalRead);
             int scanPos = pos;
-            while (scanPos < end && locBuf[scanPos] != delim1 && locBuf[scanPos] != delim2) {
-                scanPos++;
-            }
+            do {
+                char c = locBuf[scanPos];
+                if (c == delim1 || c == delim2) break;
+            } while (++scanPos < end);
             int copyLen = scanPos - pos;
             if (copyLen > 0) {
                 System.arraycopy(locBuf, pos, dest, off, copyLen);
                 off += copyLen;
                 totalRead += copyLen;
             }
+            position = scanPos;
             if (scanPos < end) {
-                // Found delimiter — don't consume it
-                position = scanPos;
-                return totalRead;
+                return totalRead;  // Found delimiter — don't consume it
             }
-            position = scanPos;
         }
 
         return totalRead;