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/app/(app)/admin/system-roles/page.tsx

@@ -0,0 +1,21 @@
+import dynamic from "next/dynamic";
+
+const SystemRolesClient = dynamic(
+  () => import("~/components/admin/SystemRolesClient.js").then((m) => m.SystemRolesClient),
+  {
+    loading: () => (
+      <div className="animate-pulse p-6 space-y-4 max-w-4xl mx-auto">
+        <div className="h-8 w-48 bg-gray-200 dark:bg-gray-700 rounded" />
+        <div className="space-y-3">
+          {[...Array(5)].map((_, i) => (
+            <div key={i} className="h-24 w-full bg-gray-200 dark:bg-gray-700 rounded-xl" />
+          ))}
+        </div>
+      </div>
+    ),
+  },
+);
+
+export default function SystemRolesPage() {
+  return <SystemRolesClient />;
+}