feat(dashboard): add GET /api/dashboard/ stats endpoint

- Active jobs count, total backups, storage used
- Recent failures (24h) and last 10 executions
- Uses DashboardStats schema

backend/app/routers/dashboard.py

@@ -1,4 +1,54 @@
-from fastapi import APIRouter
+from fastapi import APIRouter, Depends
+from sqlalchemy.ext.asyncio import AsyncSession
+from sqlalchemy import select, func, and_
+from datetime import datetime, timezone, timedelta
+from typing import List
+
+from app.database import get_db
+from app.models import Job, JobExecution, Backup
+from app.schemas import DashboardStats, JobExecution as JobExecutionSchema
 
 router = APIRouter(prefix="/api/dashboard", tags=["dashboard"])
-# Will be implemented in later tasks
+
+
+@router.get("/", response_model=DashboardStats)
+async def get_dashboard_stats(db: AsyncSession = Depends(get_db)):
+    # Active jobs count (enabled jobs)
+    active_jobs_result = await db.execute(
+        select(func.count(Job.id)).where(Job.enabled == True)
+    )
+    active_jobs = active_jobs_result.scalar() or 0
+
+    # Total backups count
+    total_backups_result = await db.execute(select(func.count(Backup.id)))
+    total_backups = total_backups_result.scalar() or 0
+
+    # Storage used bytes (sum of all backup sizes)
+    storage_used_result = await db.execute(select(func.sum(Backup.size_bytes)))
+    storage_used_bytes = storage_used_result.scalar() or 0
+
+    # Recent failures count (last 24 hours)
+    twenty_four_hours_ago = datetime.now(timezone.utc) - timedelta(hours=24)
+    recent_failures_result = await db.execute(
+        select(func.count(JobExecution.id)).where(
+            and_(
+                JobExecution.status == "failed",
+                JobExecution.completed_at >= twenty_four_hours_ago,
+            )
+        )
+    )
+    recent_failures = recent_failures_result.scalar() or 0
+
+    # Recent executions (last 10, ordered by started_at desc)
+    recent_executions_result = await db.execute(
+        select(JobExecution).order_by(JobExecution.started_at.desc()).limit(10)
+    )
+    recent_executions = recent_executions_result.scalars().all()
+
+    return DashboardStats(
+        active_jobs=active_jobs,
+        total_backups=total_backups,
+        storage_used_bytes=storage_used_bytes,
+        recent_failures=recent_failures,
+        recent_executions=list(recent_executions),
+    )