Add sick routes to backend and frontend; update routing and UI components for sickness tracking

backend/src/index.js

@@ -74,6 +74,10 @@ app.use('/api/timefix', authenticateToken, timefixRouter);
 const vacationRouter = require('./routes/vacation');
 app.use('/api/vacation', authenticateToken, vacationRouter);
 
+// Sick routes (geschützt) - MIT ID-Hashing
+const sickRouter = require('./routes/sick');
+app.use('/api/sick', authenticateToken, sickRouter);
+
 // Error handling middleware
 app.use((err, req, res, next) => {
   console.error(err.stack);