feat: 完善周期报告与用户行为分析

- 支持可配置周报月报模板与登录后异步补生成\n- 增加用户行为埋点和后台分析页面\n- 移除主题额度并保留实修回顾结算\n- 修复历史会话续聊上下文丢失

ai_knowledge_base_v2/apps/backend/app/models/chat.py

@@ -70,7 +70,6 @@ class TopicSession(Base):
     message_count: Mapped[int] = mapped_column(Integer, default=0, nullable=False)
     token_input: Mapped[int] = mapped_column(Integer, default=0, nullable=False)
     token_output: Mapped[int] = mapped_column(Integer, default=0, nullable=False)
-    quota_deducted: Mapped[int] = mapped_column(Integer, default=0, nullable=False)
     recommended_homework: Mapped[str | None] = mapped_column(Text, nullable=True)
     help_card_generated: Mapped[int] = mapped_column(Integer, default=0, nullable=False)
     share_draft_generated: Mapped[int] = mapped_column(Integer, default=0, nullable=False)