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>

packages/shared/src/types/permissions.ts

@@ -49,9 +49,12 @@ export const ROLE_DEFAULT_PERMISSIONS: Record<SystemRole, PermissionKey[]> = {
 
 export function resolvePermissions(
   systemRole: SystemRole,
-  overrides?: PermissionOverrides | null
+  overrides?: PermissionOverrides | null,
+  /** Optional DB-based defaults per role. If provided, takes precedence over ROLE_DEFAULT_PERMISSIONS. */
+  roleDefaults?: Record<string, PermissionKey[]>,
 ): Set<PermissionKey> {
-  const base = new Set<PermissionKey>(ROLE_DEFAULT_PERMISSIONS[systemRole] ?? []);
+  const defaults = roleDefaults?.[systemRole] ?? ROLE_DEFAULT_PERMISSIONS[systemRole] ?? [];
+  const base = new Set<PermissionKey>(defaults);
   if (overrides?.granted) {
     for (const p of overrides.granted) base.add(p);
   }