feat: 抽卡签到功能 - 首次抽卡/三连自动签到获随机积分

- data_manager: 新增 daily_sign_in 表、has_signed_in_today、record_sign_in 方法
- utils: 新增 get_luck_description、format_sign_in_message 函数
- __init__: 新增 try_handle_daily_sign_in 签到入口
- handle_gacha/handle_triple_gacha 成功路径 finish()→send()+签到+return
- 签到失败不影响抽卡主流程，UNIQUE约束防并发重复

danding_bot/plugins/onmyoji_gacha/data_manager.py

@@ -97,8 +97,23 @@ class DataManager:
                     total_consecutive_days INTEGER DEFAULT 0
                 )
             """)
+
+            self._init_sign_in_table(cursor)
             
             conn.commit()
+
+    def _init_sign_in_table(self, cursor: sqlite3.Cursor) -> None:
+        """创建每日签到表"""
+        cursor.execute("""
+            CREATE TABLE IF NOT EXISTS daily_sign_in (
+                id INTEGER PRIMARY KEY AUTOINCREMENT,
+                user_id TEXT NOT NULL,
+                sign_date TEXT NOT NULL,
+                points_awarded INTEGER NOT NULL,
+                created_at TEXT NOT NULL,
+                UNIQUE(user_id, sign_date)
+            )
+        """)
     
     def update_achievement_progress(self, user_id: str, rarity: str) -> List[str]:
         """更新用户成就进度，返回新解锁的成就列表"""
@@ -321,6 +336,33 @@ class DataManager:
     def get_today_date(self) -> str:
         """获取当前日期字符串"""
         return datetime.datetime.now().strftime("%Y-%m-%d")
+
+    def has_signed_in_today(self, user_id: str) -> bool:
+        """检查用户今天是否已签到"""
+        today = self.get_today_date()
+        with sqlite3.connect(config.DB_FILE) as conn:
+            cursor = conn.cursor()
+            cursor.execute(
+                "SELECT 1 FROM daily_sign_in WHERE user_id = ? AND sign_date = ? LIMIT 1",
+                (user_id, today),
+            )
+            return cursor.fetchone() is not None
+
+    def record_sign_in(self, user_id: str, points_awarded: int) -> bool:
+        """记录每日签到，重复签到返回False"""
+        today = self.get_today_date()
+        created_at = datetime.datetime.now().isoformat()
+        try:
+            with sqlite3.connect(config.DB_FILE) as conn:
+                cursor = conn.cursor()
+                cursor.execute("""
+                    INSERT INTO daily_sign_in (user_id, sign_date, points_awarded, created_at)
+                    VALUES (?, ?, ?, ?)
+                """, (user_id, today, points_awarded, created_at))
+                conn.commit()
+                return True
+        except sqlite3.IntegrityError:
+            return False
     
     def get_current_time(self) -> str:
         """获取当前时间字符串"""
@@ -549,4 +591,4 @@ class DataManager:
         
         # 更新成就进度
         unlocked_achievements = self.update_achievement_progress(user_id, rarity)
-        return unlocked_achievements
+        return unlocked_achievements