chore(db): set 30min before offline for battery endpoint

Signed-off-by: Klagarge <remi@heredero.ch>

db/src/rest/rest.go

@@ -110,7 +110,7 @@ func (g *RestGateway) getBattery(c *gin.Context) {
 
 	nodeFilter := buildNodeFilter(allNodes)
 	query := fmt.Sprintf(
-		`SELECT "node", "battery" FROM "%s" WHERE %s AND time > now() - INTERVAL '3 hour' ORDER BY time DESC`,
+		`SELECT "node", "battery" FROM "%s" WHERE %s AND time > now() - INTERVAL '30 minutes' ORDER BY time DESC`,
 		g.measurementName, nodeFilter,
 	)
 
@@ -154,7 +154,7 @@ func (g *RestGateway) getBattery(c *gin.Context) {
 		}
 		battery, hasData := nodeBattery[nodeID]
 		if !hasData {
-			battery = "offline (3h)"
+			battery = "offline (30 min)"
 		}
 		result[room][nodeID] = map[string]any{"battery": battery}
 	}