Document the WebSocket-only constraint on segment size

The storeAndForwardMaxSegmentBytes javadoc omitted the "WebSocket
transport only" sentence that storeAndForwardDir,
storeAndForwardDurability and storeAndForwardMaxTotalBytes all carry,
even though the setter throws for HTTP, TCP and UDP.

The javadoc now states that constraint, names sf_max_segment_bytes so
a reader can connect the builder method to the connect-string key, and
documents the parameter. It gives the default as a plain 4 MiB rather
than as DEFAULT_SEGMENT_BYTES, a private constant that resolves to
nothing in published javadoc. The paragraph is re-flowed to the
surrounding width.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

Author: mtopolnik

core/src/main/java/io/questdb/client/Sender.java

@@ -2770,10 +2770,12 @@ public LineSenderBuilder storeAndForwardDurability(SfDurability durability) {
         }
 
         /**
-         * Maximum bytes per segment file before rotation. Defaults to
-         * {@code DEFAULT_SEGMENT_BYTES}
-         * (4 MiB). Smaller segments mean faster trim of acked data; larger
-         * segments mean fewer rotations.
+         * Maximum bytes per segment file before rotation, the builder form of
+         * the {@code sf_max_segment_bytes} connect-string key. Smaller segments
+         * mean faster trim of acked data; larger segments mean fewer rotations.
+         * Default: {@code 4 MiB}. WebSocket transport only.
+         *
+         * @param maxSegmentBytes per-segment cap in bytes; must be positive
          */
         public LineSenderBuilder storeAndForwardMaxSegmentBytes(long maxSegmentBytes) {
             if (protocol != PARAMETER_NOT_SET_EXPLICITLY && protocol != PROTOCOL_WEBSOCKET) {