fix: handle empty segment array in TimelineSegments props update (#331)

The propSegments useEffect guard used propSegments.length > 0 which
blocked the props-based update path when all recordings were deleted
(empty array case). While the timelineState subscription compensated for
this via its own update path, the guard was semantically incorrect.

Replace the length guard with Array.isArray() so that any valid array
(including an empty one after all recordings are deleted) correctly
updates the component's local segment state via both the props path and
the subscription path.

Author: matteius

web/js/components/preact/timeline/TimelineSegments.jsx

@@ -21,9 +21,9 @@ export function TimelineSegments({ segments: propSegments }) {
   const [endHour, setEndHour] = useState(24);
   const currentSegmentIndexRef = useRef(-1);
 
-  // Update segments when props change
+  // Update segments when props change (including when cleared to empty on deletion)
   useEffect(() => {
-    if (propSegments && propSegments.length > 0) {
+    if (Array.isArray(propSegments)) {
       setSegments(propSegments);
     }
   }, [propSegments]);