Complete Phase 2: Frontend implementation with React + TypeScript

Frontend Features:
- React 18 + Vite + TypeScript + Tailwind CSS + Zustand
- JWT authentication with automatic token refresh
- Tree library with search and category filtering
- Full tree navigation (decision/action/solution nodes)
- Session management with notes and completion
- Session history with export (Markdown/Text/HTML)
- ErrorBoundary for graceful error handling

Backend Fixes:
- CORS: Added port 5174 to allowed origins
- Sessions: Fixed JSONB datetime serialization (mode='json')

Documentation:
- Updated PROGRESS.md with Phase 2 completion
- Updated 03-DEVELOPMENT-ROADMAP.md with checked items
- Added PHASE-2.5-PERSONAL-BRANCHING.md spec

Seed Data:
- Added backend/scripts/seed_data.py with Password Reset tree

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

frontend/src/components/common/RouteError.tsx

@@ -0,0 +1,52 @@
+import { useRouteError, isRouteErrorResponse, useNavigate } from 'react-router-dom'
+import { cn } from '@/lib/utils'
+
+export function RouteError() {
+  const error = useRouteError()
+  const navigate = useNavigate()
+
+  let errorMessage = 'An unexpected error occurred'
+  let errorDetails = ''
+
+  if (isRouteErrorResponse(error)) {
+    errorMessage = error.status === 404 ? 'Page not found' : `Error ${error.status}`
+    errorDetails = error.statusText || ''
+  } else if (error instanceof Error) {
+    errorMessage = 'Something went wrong'
+    errorDetails = error.message
+  }
+
+  return (
+    <div className="flex min-h-screen flex-col items-center justify-center bg-background p-8">
+      <div className="max-w-md text-center">
+        <h1 className="mb-2 text-4xl font-bold text-foreground">Oops!</h1>
+        <h2 className="mb-2 text-xl font-semibold text-foreground">{errorMessage}</h2>
+        {errorDetails && (
+          <p className="mb-4 text-muted-foreground">{errorDetails}</p>
+        )}
+        <div className="flex justify-center gap-4">
+          <button
+            onClick={() => navigate(-1)}
+            className={cn(
+              'rounded-md border border-input px-4 py-2 text-sm font-medium',
+              'hover:bg-accent hover:text-accent-foreground'
+            )}
+          >
+            Go Back
+          </button>
+          <button
+            onClick={() => navigate('/trees')}
+            className={cn(
+              'rounded-md bg-primary px-4 py-2 text-sm font-medium text-primary-foreground',
+              'hover:bg-primary/90'
+            )}
+          >
+            Go Home
+          </button>
+        </div>
+      </div>
+    </div>
+  )
+}
+
+export default RouteError