feat(api): 集成后端API，实现数据持久化和用户登录

- 新增token管理和用户信息状态，支持基于token的自动登录
- 实现登录或注册接口调用，自动根据URL参数完成身份验证
- 从后端加载交易记录、消息和待办提醒，替代本地缓存读写
- 对交易记录的增删改操作同步到数据库，确保数据一致性
- 对消息和提醒的增删改操作支持服务器同步，提升数据可靠性
- 优化消息发送逻辑，先保存用户消息，再处理AI回复并存库
- 添加待办提醒切换状态API调用，确保状态同步服务器
- 改进界面互动，支持文件与头像上传功能，更新管家形象
- 采用异步处理并增加错误捕获和用户提示，增强稳定性

components/LedgerPage.tsx

@@ -6,8 +6,8 @@ import BillReminders, { getDaysRemaining } from './BillReminders';
 
 interface LedgerPageProps {
   transactions: Transaction[];
-  onUpdateTransaction: (t: Transaction) => void;
-  onDeleteTransaction: (id: string) => void;
+  onUpdateTransaction: (t: Transaction) => Promise<void>;
+  onDeleteTransaction: (id: string) => Promise<void>;
   budgets: Record<string, number>;
   setBudgets: (val: Record<string, number>) => void;
   reminders: BillReminder[];
@@ -200,7 +200,24 @@ const LedgerPage: React.FC<LedgerPageProps> = ({
                 {subTab === 'calendar' && <CalendarView transactions={transactions} reminders={reminders} viewDate={selectedMonth} />}
                 {subTab === 'bills' && <BillReminders reminders={reminders.filter(r => r.frequency === 'monthly' || r.targetDate.startsWith(selectedMonth))} onAdd={onAddReminder} onUpdate={onUpdateReminder} onDelete={onDeleteReminder} onToggle={onToggleReminder} />}
           </div>
-          {editingTransaction && <EditTransactionModal transaction={editingTransaction} onSave={(updated) => { onUpdateTransaction(updated); setEditingTransaction(null); }} onDelete={(id) => { onDeleteTransaction(id); setEditingTransaction(null); }} onClose={() => setEditingTransaction(null)} />}
+          {editingTransaction && (
+            <EditTransactionModal 
+              transaction={editingTransaction} 
+              onSave={async (updated) => { 
+                try {
+                  await onUpdateTransaction(updated); 
+                  setEditingTransaction(null); 
+                } catch (e) {
+                  // Error handled in App.tsx
+                }
+              }} 
+              onDelete={async (id) => { 
+                await onDeleteTransaction(id); 
+                setEditingTransaction(null); 
+              }} 
+              onClose={() => setEditingTransaction(null)} 
+            />
+          )}
       </div>
   );
 };