perf: SQLite WAL + 复合索引 + GZip + scheduler jitter + 构建缓存

backend/app/models/upstream.py

@@ -1,6 +1,6 @@
 from datetime import datetime, timezone
 from typing import Optional
-from sqlalchemy import Integer, String, Boolean, DateTime, Text, Float
+from sqlalchemy import Index, Integer, String, Boolean, DateTime, Text, Float
 from sqlalchemy.orm import mapped_column, Mapped
 from app.database import Base
 
@@ -36,3 +36,7 @@ class Upstream(Base):
     updated_at: Mapped[datetime] = mapped_column(
         DateTime, default=lambda: datetime.now(timezone.utc), onupdate=lambda: datetime.now(timezone.utc)
     )
+
+    __table_args__ = (
+        Index("ix_upstream_enabled", "enabled"),
+    )