Refactor global styles and enhance MITM functionality

- Updated global CSS to implement a new brand color palette and improve light/dark theme consistency.
- Enhanced the MitmServerCard component to provide clearer user feedback regarding admin privileges.
- Filtered LLM combos in the CombosPage to ensure only relevant data is displayed.
- Improved APIPageClient layout for better usability and visual consistency.
- Added functionality to save and load DNS tool states in the MITM manager.
- Updated OAuth configuration URLs for Qwen to reflect the new endpoint structure.
- Refined tunnel management logic to improve reliability and user experience.

src/app/login/page.js

@@ -82,8 +82,10 @@ export default function LoginPage() {
   }
 
   return (
-    <div className="min-h-screen flex items-center justify-center bg-bg p-4">
-      <div className="w-full max-w-md">
+    <div className="min-h-screen flex items-center justify-center bg-bg p-4 relative overflow-hidden">
+      {/* Faint grid background */}
+      <div className="landing-grid absolute inset-0 pointer-events-none" aria-hidden="true" />
+      <div className="relative z-10 w-full max-w-md">
         <div className="text-center mb-8">
           <h1 className="text-3xl font-bold text-primary mb-2">9Router</h1>
           <p className="text-text-muted">Enter your password to access the dashboard</p>