feat: enhance user API key management and implement soft delete

- Redirect users to API Keys tab after login instead of overview
- Remove Token Limit and Daily Cost Limit from user API key details modal
- Implement soft delete for API keys to preserve usage statistics
- Add admin endpoint to view deleted API keys with metadata
- Track deletion metadata (deletedBy, deletedAt, deletedByType)
- Ensure deleted API keys cannot be restored
- Include deleted key stats in user totals while excluding from active count

🤖 Generated with [Claude Code](https://claude.ai/code)

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

src/routes/userRoutes.js

@@ -304,7 +304,7 @@ router.delete('/api-keys/:keyId', authenticateUser, async (req, res) => {
       })
     }
 
-    await apiKeyService.deleteApiKey(keyId)
+    await apiKeyService.deleteApiKey(keyId, req.user.username, 'user')
 
     // 更新用户API Key数量
     const userApiKeys = await apiKeyService.getUserApiKeys(req.user.id)