feat: Add recipe management page routing

- Import RecipePage component in App.tsx
- Register /recipe route in HashRouter
- RecipePage now accessible from RecipePanel MANAGEMENT button

Features available on /recipe page:
- Recipe list with selection
- Recipe editor with name, description, process time, temperature
- Back button to return to main page
- Add/Copy/Delete buttons (UI only, backend TBD)
- Save changes button (mock implementation)

🤖 Generated with Claude Code

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

frontend/App.tsx

@@ -3,6 +3,7 @@ import { HashRouter, Routes, Route } from 'react-router-dom';
 import { Layout } from './components/layout/Layout';
 import { HomePage } from './pages/HomePage';
 import { IOMonitorPage } from './pages/IOMonitorPage';
+import { RecipePage } from './pages/RecipePage';
 import { SystemState, Recipe, IOPoint, LogEntry, RobotTarget, ConfigItem } from './types';
 import { comms } from './communication';
 
@@ -246,6 +247,10 @@ export default function App() {
               />
             }
           />
+          <Route
+            path="/recipe"
+            element={<RecipePage />}
+          />
         </Routes>
       </Layout>
     </HashRouter>