feat: 13个统计/聚合API + 前端同步 + 待完成功能文档

API新增:
- GET /api/system/overview 系统总览(在线率/今日统计/表大小)
- GET /api/locations/stats 位置统计(类型分布/小时趋势)
- GET /api/locations/track-summary/{id} 轨迹摘要(距离/时长/速度)
- POST /api/alarms/batch-acknowledge 批量确认告警
- GET /api/attendance/report 考勤日报表(每设备每天汇总)
- GET /api/bluetooth/stats 蓝牙统计(类型/TOP信标/RSSI分布)
- GET /api/heartbeats/stats 心跳统计(活跃设备/电量/间隔分析)
- GET /api/fences/stats 围栏统计(绑定/进出状态/今日事件)
- GET /api/fences/{id}/events 围栏进出事件历史
- GET /api/commands/stats 指令统计(成功率/类型/趋势)

API增强:
- devices/stats: 新增by_type/battery_distribution/signal_distribution
- alarms/stats: 新增today/by_source/daily_trend/top_devices
- attendance/stats: 新增today/by_source/daily_trend/by_device

前端同步:
- 仪表盘: 今日告警/考勤/定位卡片 + 在线率
- 告警页: 批量确认按钮 + 今日计数
- 考勤页: 今日计数
- 轨迹: 加载后显示距离/时长/速度摘要
- 蓝牙/围栏/指令页: 统计面板

文档: CLAUDE.md待完成功能按优先级重新规划

via [HAPI](https://hapi.run)

Co-Authored-By: HAPI <noreply@hapi.run>

app/routers/commands.py

@@ -147,6 +147,74 @@ async def _send_to_device(
 # ---------------------------------------------------------------------------
 
 
+@router.get(
+    "/stats",
+    response_model=APIResponse[dict],
+    summary="指令统计 / Command statistics",
+)
+async def command_stats(
+    days: int = Query(default=7, ge=1, le=90, description="趋势天数"),
+    db: AsyncSession = Depends(get_db),
+):
+    """
+    指令统计：总数、按状态分布、按类型分布、成功率、按天趋势。
+    Command stats: total, by status, by type, success rate, daily trend.
+    """
+    from sqlalchemy import func, select
+    from datetime import timedelta
+    from app.models import CommandLog
+
+    total = (await db.execute(select(func.count(CommandLog.id)))).scalar() or 0
+
+    # By status
+    status_result = await db.execute(
+        select(CommandLog.status, func.count(CommandLog.id))
+        .group_by(CommandLog.status)
+    )
+    by_status = {row[0]: row[1] for row in status_result.all()}
+
+    # By type
+    type_result = await db.execute(
+        select(CommandLog.command_type, func.count(CommandLog.id))
+        .group_by(CommandLog.command_type)
+    )
+    by_type = {row[0]: row[1] for row in type_result.all()}
+
+    # Success rate
+    sent = by_status.get("sent", 0) + by_status.get("success", 0)
+    failed = by_status.get("failed", 0)
+    total_attempted = sent + failed
+    success_rate = round(sent / total_attempted * 100, 1) if total_attempted else 0
+
+    # Daily trend
+    now = now_cst()
+    cutoff = now - timedelta(days=days)
+    trend_result = await db.execute(
+        select(
+            func.date(CommandLog.created_at).label("day"),
+            func.count(CommandLog.id),
+        )
+        .where(CommandLog.created_at >= cutoff)
+        .group_by("day").order_by("day")
+    )
+    daily_trend = {str(row[0]): row[1] for row in trend_result.all()}
+
+    # Today
+    today_start = now.replace(hour=0, minute=0, second=0, microsecond=0)
+    today_count = (await db.execute(
+        select(func.count(CommandLog.id)).where(CommandLog.created_at >= today_start)
+    )).scalar() or 0
+
+    return APIResponse(data={
+        "total": total,
+        "today": today_count,
+        "by_status": by_status,
+        "by_type": by_type,
+        "success_rate": success_rate,
+        "daily_trend": daily_trend,
+    })
+
+
 @router.get(
     "",
     response_model=APIResponse[PaginatedList[CommandResponse]],