update data purging, re-enable channel selection

public/js/app.js

@@ -173,17 +173,17 @@ const api = {
         return this.request(`/api/messages?limit=${limit}`);
     },
 
-    async sendMessage(from, text) {
+    async sendMessage(from, text, channel) {
         return this.request('/api/messages/send', {
             method: 'POST',
-            body: JSON.stringify({ text, from })
+            body: JSON.stringify({ from, text, channel })
         });
     },
 
-    async purgeData(days) {
+    async purgeData(hours) {
         return this.request('/api/purge', {
             method: 'POST',
-            body: JSON.stringify({ days })
+            body: JSON.stringify({ hours })
         });
     },
 
@@ -547,9 +547,10 @@ document.getElementById('send-message-form')?.addEventListener('submit', async (
 
     const text = document.getElementById('message-text').value;
     const from = parseInt(document.getElementById('message-from').value);
+    const channel = parseInt(document.getElementById('message-channel').value);
 
     try {
-        await api.sendMessage(text, from);
+        await api.sendMessage(from, text, channel);
         document.getElementById('message-text').value = '';
 
         // Reload messages after a short delay
@@ -1045,14 +1046,23 @@ document.getElementById('refresh-map-btn')?.addEventListener('click', loadMap);
 document.getElementById('purge-form')?.addEventListener('submit', async (e) => {
     e.preventDefault();
 
-    const days = parseInt(document.getElementById('purge-days').value);
+    const hours = parseInt(document.getElementById('purge-hours').value);
 
-    if (!confirm(`Are you sure you want to delete data older than ${days} days? This cannot be undone.`)) {
+    // Format time period for display
+    let timePeriod;
+    if (hours < 24) {
+        timePeriod = `${hours} hour${hours !== 1 ? 's' : ''}`;
+    } else {
+        const days = hours / 24;
+        timePeriod = `${days} day${days !== 1 ? 's' : ''}`;
+    }
+
+    if (!confirm(`Are you sure you want to delete data older than ${timePeriod}? This cannot be undone.`)) {
         return;
     }
 
     try {
-        const result = await api.purgeData(days);
+        const result = await api.purgeData(hours);
         alert(`Successfully purged:\n${result.deleted.messages} messages\n${result.deleted.positions} positions\n${result.deleted.telemetry} telemetry records`);
 
         // Reload stats