Add advanced custom CSS/JS file support per template (#7361)

Introduces a new 'customFiles' array in the config schema for granular domain-level CSS and JavaScript customization. Updates webserver logic to inject custom CSS/JS tags based on template scope, replacing static custom.css/custom.js references in all Handlebars views. Also updates meshctrl.js to support the new config property.

views/message2.handlebars

@@ -8,10 +8,10 @@
     <meta name=format-detection content="telephone=no" />
     <meta name="robots" content="noindex,nofollow">
     <link type=text/css href="/styles/style.css" media="screen" rel="stylesheet" title="CSS" />
-    <link type="text/css" href="styles/custom.css" media="screen" rel="stylesheet" title="CSS" />
+    {{{customCSSTags}}}
     <link rel="apple-touch-icon" href="/favicon-303x303.png" />
     <script type="text/javascript" src="scripts/common-0.0.1{{min}}.js"></script>
-    <script type="text/javascript" src="scripts/custom.js"></script>
+    {{{customJSTags}}}
     <title id="topTitle">{{{title1}}}</title>
     <style>
         body {