feat: WordPress Monitor API + Site Availability Checker

- Add POST /api/wp-monitor endpoint for WP plugin data
- Add GET /api/wp-monitor for listing monitored sites
- Add checkSiteAvailability() function for HTTP health checks
- Add checkAllSitesAvailability() for batch checking
- Add /api/scripts/check-sites.ts for cron execution
- Add POST /api/monitor/check-sites for manual trigger

DeskCRM Task: #1556

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

api/services/monitoring.ts

@@ -25,6 +25,105 @@ interface CategorySummary {
   critical: number
 }
 
+/**
+ * Check if a URL is accessible (HTTP HEAD request)
+ */
+export async function checkSiteAvailability(url: string, timeout = 10000): Promise<{
+  available: boolean
+  statusCode?: number
+  responseTime?: number
+  error?: string
+}> {
+  const startTime = Date.now()
+  const controller = new AbortController()
+  const timeoutId = setTimeout(() => controller.abort(), timeout)
+
+  try {
+    const response = await fetch(url, {
+      method: 'HEAD',
+      signal: controller.signal,
+      headers: {
+        'User-Agent': 'Descomplicar-Monitor/1.0'
+      }
+    })
+
+    clearTimeout(timeoutId)
+    const responseTime = Date.now() - startTime
+
+    return {
+      available: response.ok || response.status < 500,
+      statusCode: response.status,
+      responseTime
+    }
+  } catch (error) {
+    clearTimeout(timeoutId)
+    return {
+      available: false,
+      error: (error as Error).message,
+      responseTime: Date.now() - startTime
+    }
+  }
+}
+
+/**
+ * Check all sites and update their availability status
+ */
+export async function checkAllSitesAvailability(): Promise<{
+  checked: number
+  up: number
+  down: number
+  results: any[]
+}> {
+  // Get all sites from monitoring table
+  const [sites] = await db.query<RowDataPacket[]>(`
+    SELECT id, name, details FROM tbl_eal_monitoring
+    WHERE category = 'site'
+  `)
+
+  const results: any[] = []
+  let up = 0
+  let down = 0
+
+  for (const site of sites) {
+    const details = typeof site.details === 'string' ? JSON.parse(site.details) : site.details
+    const siteUrl = details?.site_url || `https://${site.name}`
+
+    const check = await checkSiteAvailability(siteUrl)
+
+    // Update status if site is down
+    if (!check.available) {
+      await db.query(
+        'UPDATE tbl_eal_monitoring SET status = ?, last_check = NOW() WHERE id = ?',
+        ['down', site.id]
+      )
+      down++
+    } else {
+      // If was down and now is up, set to 'up' (will be replaced by plugin data later)
+      const currentStatus = details?.health?.status || 'ok'
+      if (currentStatus === 'down') {
+        await db.query(
+          'UPDATE tbl_eal_monitoring SET status = ?, last_check = NOW() WHERE id = ?',
+          ['up', site.id]
+        )
+      }
+      up++
+    }
+
+    results.push({
+      name: site.name,
+      url: siteUrl,
+      ...check
+    })
+  }
+
+  return {
+    checked: sites.length,
+    up,
+    down,
+    results
+  }
+}
+
 export async function getMonitoringData() {
   // Get all items
   const [items] = await db.query<RowDataPacket[]>(`