feat: add branding assets and favicon support across admin-web and desktop-client

Add NexaVPN logo images (full logo and mark-only variants) to admin-web and desktop-client public directories. Add favicon.ico and favicon.png to admin-web, and icon.png to desktop-client. Update index.html files to reference favicon assets. Add icon.png and icon.ico to desktop-client Tauri icons directory and configure bundle.icon in tauri.conf.json. Update Layout component to display logo in sidebar brand-block with

admin-web/src/components/Layout.tsx

@@ -14,9 +14,13 @@ export function Layout() {
   return (
     <div className="shell">
       <aside className="sidebar">
-        <div>
-          <p className="eyebrow">NexaVPN</p>
-          <h1>Control Plane</h1>
+        <div className="brand-block">
+          <img className="brand-logo brand-logo-full" src="/NexaVPN_Logo.png" alt="NexaVPN" />
+          <div className="brand-copy">
+            <p className="eyebrow">NexaVPN</p>
+            <h1>Control Plane</h1>
+            <p className="brand-tagline">Remote access orchestration for your private WireGuard edge.</p>
+          </div>
         </div>
         <nav className="nav">
           {items.map(([label, path]) => (
@@ -32,9 +36,12 @@ export function Layout() {
       </aside>
       <main className="content">
         <header className="topbar">
-          <div>
-            <p className="eyebrow">Enterprise WireGuard</p>
-            <h2>Self-hosted VPN management</h2>
+          <div className="topbar-brand">
+            <img className="brand-logo brand-logo-mark" src="/NexaVPN_Logo_Only.png" alt="NexaVPN mark" />
+            <div>
+              <p className="eyebrow">Enterprise WireGuard</p>
+              <h2>Self-hosted VPN management</h2>
+            </div>
           </div>
           <div className="pill">Secure by design</div>
         </header>

admin-web/src/features/auth/LoginPage.tsx

@@ -58,8 +58,13 @@ export function LoginPage({ onAuthenticated }: LoginPageProps) {
   return (
     <div className="auth-shell">
       <form className="auth-card" onSubmit={onSubmit}>
-        <p className="eyebrow">NexaVPN Admin</p>
-        <h2>{mode === "login" ? "Sign in" : "Create initial admin"}</h2>
+        <div className="auth-brand">
+          <img className="brand-logo brand-logo-full" src="/NexaVPN_Logo.png" alt="NexaVPN" />
+          <div>
+            <p className="eyebrow">NexaVPN Admin</p>
+            <h2>{mode === "login" ? "Sign in" : "Create initial admin"}</h2>
+          </div>
+        </div>
         <p className="auth-copy">
           {mode === "login"
             ? "Use your NexaVPN admin credentials."

admin-web/src/styles/global.css

@@ -61,6 +61,45 @@ button {
   backdrop-filter: blur(12px);
 }
 
+.auth-brand,
+.brand-block,
+.topbar-brand {
+  display: flex;
+  align-items: center;
+  gap: 16px;
+}
+
+.brand-block {
+  align-items: flex-start;
+}
+
+.brand-copy {
+  display: grid;
+  gap: 6px;
+}
+
+.brand-tagline {
+  margin: 0;
+  color: var(--muted);
+  max-width: 240px;
+  line-height: 1.5;
+}
+
+.brand-logo {
+  display: block;
+  height: auto;
+}
+
+.brand-logo-full {
+  width: min(100%, 220px);
+}
+
+.brand-logo-mark {
+  width: 48px;
+  border-radius: 14px;
+  box-shadow: 0 10px 30px rgba(0, 0, 0, 0.18);
+}
+
 .auth-card label {
   display: grid;
   gap: 8px;
@@ -258,6 +297,18 @@ button {
     border-bottom: 1px solid var(--line);
   }
 
+  .auth-brand,
+  .brand-block,
+  .topbar-brand,
+  .page-header {
+    align-items: flex-start;
+    flex-direction: column;
+  }
+
+  .brand-logo-full {
+    width: min(100%, 200px);
+  }
+
   .grid.two,
   .grid.three {
     grid-template-columns: 1fr;