fix: hover card, preferences modal, timeline scroll, multi-drag

- ResourceHoverCard: add isInitialLoading to useEffect deps so
  mouseover/mouseout listeners attach after canvas mounts
- PreferencesModal: lift prefsOpen state to AppShell, render modal
  outside sidebar's backdrop-blur stacking context
- Timeline page: constrain to max-h-[100dvh] overflow-hidden so
  horizontal scrollbar is accessible without scrolling to bottom
- Multi-drag: pass selectedAllocationIds from ref at drag completion
  to prevent stale closure in onMultiDragComplete callback

Co-Authored-By: claude-flow <ruv@ruv.net>

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

@@ -135,8 +135,8 @@ export function TimelineView() {
         return { ...prev, isSelecting: false, selectedAllocationIds: [...ids] };
       });
     },
-    onMultiDragComplete: (daysDelta, mode) => {
-      const ids = multiSelectState.selectedAllocationIds;
+    onMultiDragComplete: (daysDelta, mode, selectedIds) => {
+      const ids = selectedIds ?? multiSelectState.selectedAllocationIds;
       if (ids.length > 0 && daysDelta !== 0) {
         pushBatchHistoryRef.current(ids, daysDelta, mode);
         batchShiftMutationOuter.mutate({ allocationIds: ids, daysDelta, mode });
@@ -547,7 +547,7 @@ function TimelineViewContent({
         resourceHoverTimerRef.current = null;
       }
     };
-  }, [resourceHover?.resourceId]); // eslint-disable-line react-hooks/exhaustive-deps
+  }, [resourceHover?.resourceId, isInitialLoading]); // eslint-disable-line react-hooks/exhaustive-deps
 
   // ─── Lazy-extend date range on scroll ─────────────────────────────────────
   function handleContainerScroll() {