feat: timeline multi-select, demand popover, resource hover card, merged tooltips, dark mode fixes

Major timeline enhancements:
- Right-click drag multi-selection with floating action bar (batch delete/assign)
- DemandPopover for demand strip details (replaces broken "Loading" modal)
- ResourceHoverCard on name hover showing skills, rates, role, chapter
- Merged heatmap+vacation tooltips into unified TimelineTooltip component
- Fixed overbooking blink animation (date normalization, z-index ordering)
- Fixed dark mode sticky column bleed-through in project view
- System roles admin page, notification task management, performance review docs

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

apps/web/src/components/allocations/AllocationModal.tsx

@@ -23,7 +23,10 @@ interface AllocationModalProps {
 function toDateInputValue(date: Date | string | null | undefined): string {
   if (!date) return "";
   const d = typeof date === "string" ? new Date(date) : date;
-  return d.toISOString().split("T")[0] ?? "";
+  const y = d.getFullYear();
+  const m = String(d.getMonth() + 1).padStart(2, "0");
+  const day = String(d.getDate()).padStart(2, "0");
+  return `${y}-${m}-${day}`;
 }
 
 export function AllocationModal({ allocation, onClose, onSuccess }: AllocationModalProps) {