feat: 核心模块增强 — 加密 + 运行时配置 + 日志缓冲

- crypto.py: API Key 加密/解密工具
- runtime_config.py: 运行时动态配置管理
- log_buffer.py: 内存日志缓冲区
- config.py: 新增加密配置项
- http_client.py: 增强重试和错误处理

src/db/models.py

@@ -177,6 +177,9 @@ class Prediction(Base):
     latency_ms: Mapped[int | None] = mapped_column(Integer)
     pred_home_goals: Mapped[float | None] = mapped_column(Float)
     pred_away_goals: Mapped[float | None] = mapped_column(Float)
+    # 备选比分(次可能比分,可空)
+    alt_pred_home_goals: Mapped[int | None] = mapped_column(Integer)
+    alt_pred_away_goals: Mapped[int | None] = mapped_column(Integer)
     pred_1x2: Mapped[str | None] = mapped_column(String(3))
     subjective_confidence: Mapped[float | None] = mapped_column(Float)  # LLM 主观置信度,非概率
     reasoning: Mapped[str | None] = mapped_column(Text)
@@ -216,3 +219,12 @@ class Prediction(Base):
         CheckConstraint("mode IN ('single', 'multi')", name="ck_mode_enum"),
         CheckConstraint("status IN ('success', 'failed', 'degraded')", name="ck_status_enum"),
     )
+
+
+class AppSetting(Base):
+    """后台管理的运行时设置(如数据源 API Key),读取时优先于 .env 默认值。"""
+    __tablename__ = "app_settings"
+
+    key: Mapped[str] = mapped_column(String(100), primary_key=True)
+    value: Mapped[str] = mapped_column(Text, nullable=False)
+    updated_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), default=_utcnow, onupdate=_utcnow)