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/ErrorBoundary.tsx

@@ -0,0 +1,48 @@
+import React from 'react';
+
+interface Props { children: React.ReactNode; }
+interface State { hasError: boolean; error: Error | null; }
+
+export class ErrorBoundary extends React.Component<Props, State> {
+    constructor(props: Props) {
+        super(props);
+        this.state = { hasError: false, error: null };
+    }
+
+    static getDerivedStateFromError(error: Error): State {
+        return { hasError: true, error };
+    }
+
+    componentDidCatch(error: Error, errorInfo: React.ErrorInfo) {
+        console.error('ErrorBoundary caught:', error, errorInfo);
+    }
+
+    render() {
+        if (this.state.hasError) {
+            return (
+                <div style={{
+                    display: 'flex', alignItems: 'center', justifyContent: 'center',
+                    minHeight: '100vh', background: '#0a0f1a', color: '#e2e8f0',
+                    fontFamily: '"DM Sans", sans-serif', flexDirection: 'column', gap: 16,
+                }}>
+                    <div style={{ fontSize: 48 }}>⚠️</div>
+                    <h1 style={{ fontSize: 24, fontWeight: 700 }}>Something went wrong</h1>
+                    <p style={{ color: '#94a3b8', maxWidth: 400, textAlign: 'center', lineHeight: 1.6 }}>
+                        {this.state.error?.message || 'An unexpected error occurred.'}
+                    </p>
+                    <button
+                        onClick={() => { this.setState({ hasError: false, error: null }); window.location.reload(); }}
+                        style={{
+                            background: '#6366f1', color: '#fff', border: 'none', borderRadius: 8,
+                            padding: '10px 24px', fontSize: 14, fontWeight: 600, cursor: 'pointer',
+                            marginTop: 8,
+                        }}
+                    >
+                        Reload App
+                    </button>
+                </div>
+            );
+        }
+        return this.props.children;
+    }
+}