feat(db): health check now pings SQLite DB for real status

backend/app/routers/health.py

@@ -1,35 +1,47 @@
 import time
 from datetime import datetime, timezone
 
-from fastapi import APIRouter
+from fastapi import APIRouter, Depends
+from sqlalchemy import text
+from sqlalchemy.orm import Session
 
+from app.database import get_db
 from app.schemas import HealthCheck, HealthResponse
 
 router = APIRouter(tags=['health'])
 START_TIME = time.time()
 
 
-def build_health() -> HealthResponse:
+def build_health(db: Session) -> HealthResponse:
+    db_check: HealthCheck
+    try:
+        t0 = time.perf_counter()
+        db.execute(text("SELECT 1"))
+        latency_ms = round((time.perf_counter() - t0) * 1000, 2)
+        db_check = HealthCheck(status='pass', latency_ms=latency_ms, detail='sqlite ok')
+    except Exception as exc:
+        db_check = HealthCheck(status='fail', detail=str(exc))
+    overall = 'pass' if db_check.status == 'pass' else 'fail'
     return HealthResponse(
-        status='pass',
+        status=overall,
         service='netmapper-backend',
         version='0.1.0',
         time=datetime.now(timezone.utc),
         uptime_s=round(time.time() - START_TIME, 2),
-        checks={'db': HealthCheck(status='warn', detail='database not configured yet')},
+        checks={'db': db_check},
     )
 
 
 @router.get('/live', response_model=HealthResponse)
-def live() -> HealthResponse:
-    return build_health()
+def live(db: Session = Depends(get_db)) -> HealthResponse:
+    return build_health(db)
 
 
 @router.get('/ready', response_model=HealthResponse)
-def ready() -> HealthResponse:
-    return build_health()
+def ready(db: Session = Depends(get_db)) -> HealthResponse:
+    return build_health(db)
 
 
 @router.get('/health', response_model=HealthResponse)
-def health() -> HealthResponse:
-    return build_health()
+def health(db: Session = Depends(get_db)) -> HealthResponse:
+    return build_health(db)