备份：PWA配置前的完整版本

包含所有最新开发的功能和修复，作为PWA正确配置前的备份点。

backend/routes/purchase.js

@@ -128,7 +128,7 @@ router.post('/', async (req, res) => {
       VALUES ($1, $2, $3, $4, $5, $6, $7, CURRENT_TIMESTAMP, CURRENT_TIMESTAMP)
        RETURNING id`,
       [requestCode, project_id, purchase_type || 'inventory', total_amount || 0, currency || 'CNY', 
-        'pending_edit', remark]);
+        'pending', remark]);
     
     res.json({
       success: true,
@@ -219,7 +219,7 @@ router.post('/:id/submit', async (req, res) => {
     const { id } = req.params;
     
     const result = await db.query(
-      'UPDATE purchase_requests SET status = $1, updated_at = datetime(\'now\') WHERE id = $2', 
+      'UPDATE purchase_requests SET status = $1, updated_at = CURRENT_TIMESTAMP WHERE id = $2', 
       ['pending', id]
     );
     
@@ -256,7 +256,7 @@ router.post('/:id/approve', async (req, res) => {
     
     try {
       await db.query(
-        'UPDATE purchase_requests SET status = $1, updated_at = datetime(\'now\') WHERE id = $2',
+        'UPDATE purchase_requests SET status = $1, updated_at = CURRENT_TIMESTAMP WHERE id = $2',
         ['approved', id]
       );
       
@@ -297,8 +297,8 @@ router.post('/:id/reject', async (req, res) => {
     const { id } = req.params;
     
     const result = await db.query(
-      'UPDATE purchase_requests SET status = $1, updated_at = datetime(\'now\') WHERE id = $2', 
-      ['pending_edit', id]
+      'UPDATE purchase_requests SET status = $1, updated_at = CURRENT_TIMESTAMP WHERE id = $2', 
+      ['pending', id]
     );
     
     if (result.rowCount === 0) {
@@ -321,7 +321,7 @@ router.post('/:id/withdraw', async (req, res) => {
     const { id } = req.params;
     
     const result = await db.query(
-      'UPDATE purchase_requests SET status = $1, updated_at = datetime(\'now\') WHERE id = $2', 
+      'UPDATE purchase_requests SET status = $1, updated_at = CURRENT_TIMESTAMP WHERE id = $2', 
       ['withdrawn', id]
     );
     
@@ -345,7 +345,7 @@ router.post('/:id/execute', async (req, res) => {
     const { id } = req.params;
     
     await db.query(
-      'UPDATE purchase_requests SET status = $1, updated_at = datetime(\'now\') WHERE id = $2', 
+      'UPDATE purchase_requests SET status = $1, updated_at = CURRENT_TIMESTAMP WHERE id = $2', 
       ['executed', id]
     );