refactor: update module docstrings for clarity and consistency

backend/app/schemas/board_group_heartbeat.py

@@ -1,13 +1,18 @@
+"""Schemas for applying heartbeat settings to board-group agents."""
+
 from __future__ import annotations
 
 from typing import Any
-from uuid import UUID
+from uuid import UUID  # noqa: TCH003
 
 from sqlmodel import SQLModel
 
 
 class BoardGroupHeartbeatApply(SQLModel):
-    # Heartbeat cadence string understood by the OpenClaw gateway (e.g. "2m", "10m", "30m").
+    """Request payload for heartbeat policy updates."""
+
+    # Heartbeat cadence string understood by the OpenClaw gateway
+    # (e.g. "2m", "10m", "30m").
     every: str
     # Optional heartbeat target (most deployments use "none").
     target: str | None = None
@@ -15,6 +20,8 @@ class BoardGroupHeartbeatApply(SQLModel):
 
 
 class BoardGroupHeartbeatApplyResult(SQLModel):
+    """Result payload describing agents updated by a heartbeat request."""
+
     board_group_id: UUID
     requested: dict[str, Any]
     updated_agent_ids: list[UUID]