feat: complete Scrum-manager MVP — dark-themed multi-user task manager

- Login with role-based auth (CTO/Manager/Employee)
- Calendar view (month/week) with task chips and quick-add
- Kanban board with status columns
- Sortable list view with action menus
- Task detail drawer with subtasks, comments, activity
- Add task modal with validation
- Dashboard with stats, workload, priority breakdown
- Team tasks grouped by assignee
- Reports page with recharts (bar, pie, line, horizontal bar)
- Members page with invite modal
- Search and assignee filter across views
- ErrorBoundary for production error handling
- Full dark design system via index.css

src/Sidebar.tsx

@@ -0,0 +1,52 @@
+import type { User } from './data';
+import { Avatar } from './Shared';
+import { RoleBadge } from './Shared';
+
+const NAV_ITEMS = [
+    { id: 'dashboard', icon: '⊞', label: 'Dashboard', roles: ['cto', 'manager', 'employee'] },
+    { id: 'calendar', icon: '📅', label: 'Calendar', roles: ['cto', 'manager', 'employee'] },
+    { id: 'kanban', icon: '▦', label: 'Kanban Board', roles: ['cto', 'manager', 'employee'] },
+    { id: 'mytasks', icon: '✓', label: 'My Tasks', roles: ['employee'] },
+    { id: 'teamtasks', icon: '👥', label: 'Team Tasks', roles: ['cto', 'manager'] },
+    { id: 'reports', icon: '📊', label: 'Reports', roles: ['cto', 'manager'] },
+    { id: 'members', icon: '👤', label: 'Members', roles: ['cto'] },
+];
+
+interface SidebarProps {
+    currentUser: User;
+    activePage: string;
+    onNavigate: (page: string) => void;
+    onSignOut: () => void;
+}
+
+export function Sidebar({ currentUser, activePage, onNavigate, onSignOut }: SidebarProps) {
+    const filteredNav = NAV_ITEMS.filter(n => n.roles.includes(currentUser.role));
+    return (
+        <div className="sidebar">
+            <div className="sidebar-logo">
+                <div className="sidebar-logo-icon">⚡</div>
+                <span className="sidebar-logo-text">Scrum-manager</span>
+            </div>
+            <div className="sidebar-divider" />
+            <div className="sidebar-section-label">Navigate</div>
+            <nav className="sidebar-nav">
+                {filteredNav.map(n => (
+                    <div key={n.id} className={`sidebar-item ${activePage === n.id ? 'active' : ''}`} onClick={() => onNavigate(n.id)}>
+                        <span className="sidebar-item-icon">{n.icon}</span>
+                        {n.label}
+                    </div>
+                ))}
+            </nav>
+            <div className="sidebar-profile">
+                <Avatar userId={currentUser.id} size={36} />
+                <div className="sidebar-profile-info">
+                    <div className="sidebar-profile-name">{currentUser.name}</div>
+                    <RoleBadge role={currentUser.role} />
+                </div>
+            </div>
+            <div style={{ padding: '0 16px 12px' }}>
+                <button className="sidebar-signout" onClick={onSignOut}>Sign Out</button>
+            </div>
+        </div>
+    );
+}