feat(backend): history keys cover the profile fields, group snapshots keyed by time, indexes for memberships and job lookups

backend/src/utils/db/models.py

@@ -356,7 +356,7 @@ class ChatHistory(SQLModel, table=True):
     title: str | None = None
     photo_unique_id: str | None = None
     actor_id: int | None = Field(default=None, sa_column=Column(BigInteger))
-    ts: datetime = Field(sa_column=Column(DateTime(timezone=True), nullable=False))
+    ts: datetime = Field(sa_column=Column(DateTime(timezone=True), primary_key=True))
     raw: dict[str, Any] = Field(
         default_factory=dict, sa_column=Column(JSONB, nullable=False)
     )