Fix equipment charts to display full 24-hour time range

Set explicit min/max bounds on chart x-axis to ensure all graphs
consistently show 24 hours of data, even when data points are sparse.

Also fix AlertNotifierTest race condition by disabling async execution.

assets/js/app.js

@@ -194,6 +194,10 @@ const SensorChart = {
       }
     }
 
+    // Calculate 24-hour time range for consistent x-axis
+    const now = Date.now()
+    const twentyFourHoursAgo = now - (24 * 60 * 60 * 1000)
+
     this.chart = new Chart(ctx, {
       type: chartType,
       data: { datasets },
@@ -240,11 +244,11 @@ const SensorChart = {
         scales: {
           x: {
             type: 'linear',
+            min: twentyFourHoursAgo,
+            max: now,
             ticks: {
-              callback: function(value, index) {
-                const point = this.chart.data.datasets[0]?.data[index]
-                if (!point) return ''
-                const date = new Date(point.x)
+              callback: function(value) {
+                const date = new Date(value)
                 return date.toLocaleTimeString('en-US', { hour: '2-digit', minute: '2-digit', hour12: false })
               },
               maxTicksLimit: 12

test/towerops/alerts/alert_notifier_test.exs

@@ -1,5 +1,5 @@
 defmodule Towerops.Alerts.AlertNotifierTest do
-  use Towerops.DataCase
+  use Towerops.DataCase, async: false
 
   import Swoosh.TestAssertions
   import Towerops.AccountsFixtures