fix(timeline): trigger scroll-to-today on isInitialLoading→false not totalCanvasWidth

totalCanvasWidth is computed from viewStart/viewDays before data loads,
so the previous trigger fired during the loading spinner. scrollLeft
was clipped to 0 (no canvas in DOM yet) and the guard was set, blocking
the real scroll after data arrived. Using isInitialLoading as the dep
fires the effect exactly when the canvas enters the DOM.

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

apps/web/src/components/timeline/TimelineView.tsx

@@ -698,16 +698,16 @@ function TimelineViewContent({
     };
   }, []);
 
-  // Scroll to today the first time the canvas has its full width (after initial data load).
+  // Scroll to today the first time the canvas is in the DOM (isInitialLoading → false).
-  // Depends on totalCanvasWidth so it fires after isInitialLoading → false renders the canvas.
+  // totalCanvasWidth is non-zero before data loads, so it can't be used as the trigger.
   useLayoutEffect(() => {
-    if (totalCanvasWidth === 0) return;
+    if (isInitialLoading) return;
     if (hasScrolledToTodayOnLoad.current) return;
     const el = scrollContainerRef.current;
     if (!el) return;
     el.scrollLeft = toLeft(today);
     hasScrolledToTodayOnLoad.current = true;
-  }, [totalCanvasWidth, toLeft, today]);
+  }, [isInitialLoading, toLeft, today]);
 
   // Apply scroll compensation synchronously after the canvas grows (left-extend or Today button).
   useLayoutEffect(() => {