feat: full de-Angularization with Bootstrap 5 migration

- Removed AngularJS 1.4.8 completely — no more framework dependency
- Extracted core RCON logic into pure vanilla JS (js/rcon.js)
- Added lightweight hash-based SPA router (js/router.js)
- Rewrote all 6 pages as vanilla JS modules in js/pages/
- Migrated Bootstrap 3 → Bootstrap 5 (cards instead of panels, bootstrap-icons instead of glyphicons)
- Removed jQuery dependency (Bootstrap 5 is vanilla JS)
- Purged all Angular templates from html/
- Removed npm artifacts (package.json, node_modules)
- Added nginx.example.conf for static hosting
- Updated rcon.css dark theme for BS5 variables
- Static file only — no Node.js backend required

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

js/utils.js

@@ -0,0 +1,47 @@
+/**
+ * Utility functions shared across pages.
+ */
+
+/**
+ * Convert seconds to a human-readable duration string.
+ * e.g., 3723 → "1h2m3s"
+ */
+function secondsToDuration(input) {
+  input = parseInt(input, 10);
+  if (isNaN(input)) return '0s';
+
+  var out = '';
+  var hours = Math.floor(input / 3600);
+  if (hours > 0) out += hours + 'h';
+
+  var minutes = Math.floor((input % 3600) / 60);
+  if (minutes > 0) out += minutes + 'm';
+
+  var seconds = input % 60;
+  out += seconds + 's';
+
+  return out;
+}
+
+/**
+ * Strip HTML tags from a string.
+ */
+function stripHtml(text) {
+  return text ? String(text).replace(/<[^>]+>/gm, '') : '';
+}
+
+/**
+ * Format a number with locale-aware separators (fallback).
+ */
+function formatNumber(n) {
+  n = parseInt(n, 10);
+  if (isNaN(n)) return '0';
+  return n.toLocaleString ? n.toLocaleString() : String(n);
+}
+
+/**
+ * Check if user is scrolled to the bottom of an element.
+ */
+function isScrolledToBottom(el) {
+  return (el.scrollTop + el.clientHeight) >= (el.scrollHeight - 10);
+}