fix: 修复时区问题和翻译状态更新问题

- 使用上海时区（UTC+8）判断每日次数重置，而不是UTC时间
- 翻译任务完成后更新数据库Translation记录的状态和进度
- 传入translation_id和app到TranslationTask以支持数据库状态同步

services.py

@@ -255,7 +255,7 @@ class TranslationTask:
     lock = threading.Lock()
     
     @classmethod
-    def create_task(cls, task_id, pdf_path, output_path, config, instruction=None):
+    def create_task(cls, task_id, pdf_path, output_path, config, instruction=None, translation_id=None, app=None):
         """创建翻译任务"""
         task = {
             'id': task_id,
@@ -266,6 +266,7 @@ class TranslationTask:
             'error': None,
             'started_at': None,
             'completed_at': None,
+            'translation_id': translation_id,
         }
         
         with cls.lock:
@@ -277,10 +278,28 @@ class TranslationTask:
             task['status'] = 'processing'
             task['started_at'] = datetime.now().isoformat()
             
+            # 更新数据库状态为 processing
+            if app and translation_id:
+                with app.app_context():
+                    from models import db, Translation
+                    trans = Translation.query.get(translation_id)
+                    if trans:
+                        trans.status = 'processing'
+                        db.session.commit()
+            
             def progress_callback(progress, total, message):
                 with cls.lock:
                     task['progress'] = progress
                     task['message'] = message
+                
+                # 更新数据库进度
+                if app and translation_id:
+                    with app.app_context():
+                        from models import db, Translation
+                        trans = Translation.query.get(translation_id)
+                        if trans:
+                            trans.progress = progress
+                            db.session.commit()
             
             try:
                 result = service.translate_pdf(
@@ -291,11 +310,32 @@ class TranslationTask:
                 task['message'] = '翻译完成'
                 task['completed_at'] = datetime.now().isoformat()
                 task['result'] = result
+                
+                # 更新数据库状态为 completed
+                if app and translation_id:
+                    with app.app_context():
+                        from models import db, Translation
+                        trans = Translation.query.get(translation_id)
+                        if trans:
+                            trans.status = 'completed'
+                            trans.progress = 100
+                            trans.completed_at = datetime.now()
+                            db.session.commit()
             
             except Exception as e:
                 task['status'] = 'failed'
                 task['error'] = str(e)
                 task['message'] = f'翻译失败: {e}'
+                
+                # 更新数据库状态为 failed
+                if app and translation_id:
+                    with app.app_context():
+                        from models import db, Translation
+                        trans = Translation.query.get(translation_id)
+                        if trans:
+                            trans.status = 'failed'
+                            trans.error_message = str(e)
+                            db.session.commit()
         
         thread = threading.Thread(target=run_translation)
         thread.start()