fix: resolve SonarQube findings and Next.js Image warnings

SonarQube/SonarLint fixes:
- Remove unused imports (useMemo, PROVIDER_ENDPOINTS, updateSettings, APP_CONFIG)
- Add PropTypes validation to all components receiving props
- Fix accessibility issues (semantic buttons, ARIA attributes, form labels)
- Replace array index keys with stable identifiers
- Extract duplicate getStatusDisplay function in providers page
- Fix negated conditions for better readability
- Add node: prefix to Node.js imports in localDb.js
- Fix optional chaining in pricing lookup
- Add explanatory comments to empty catch blocks
- Consolidate duplicate OAuth flow branches
- Change parseInt to Number.parseInt
- Disable false positive rules in VS Code settings

Next.js Image fixes:
- Add style={{ width: "auto", height: "auto" }} to all Image components
- Resolves aspect ratio warnings without triggering lint issues

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/app/landing/components/Navigation.js

@@ -10,12 +10,17 @@ export default function Navigation() {
     <nav className="fixed top-0 z-50 w-full bg-[#181411]/80 backdrop-blur-md border-b border-[#3a2f27]">
       <div className="max-w-7xl mx-auto px-6 h-16 flex items-center justify-between">
         {/* Logo */}
-        <div className="flex items-center gap-3 cursor-pointer" onClick={() => router.push("/")}>
+        <button
+          type="button"
+          className="flex items-center gap-3 cursor-pointer bg-transparent border-none p-0"
+          onClick={() => router.push("/")}
+          aria-label="Navigate to home"
+        >
           <div className="size-8 rounded bg-linear-to-br from-[#f97815] to-orange-700 flex items-center justify-center text-white">
             <span className="material-symbols-outlined text-[20px]">hub</span>
           </div>
           <h2 className="text-white text-xl font-bold tracking-tight">9Router</h2>
-        </div>
+        </button>
 
         {/* Desktop menu */}
         <div className="hidden md:flex items-center gap-8">

src/app/landing/page.js

@@ -1,4 +1,5 @@
 "use client";
+import { useRouter } from "next/navigation";
 import Navigation from "./components/Navigation";
 import HeroSection from "./components/HeroSection";
 import FlowAnimation from "./components/FlowAnimation";
@@ -8,6 +9,7 @@ import GetStarted from "./components/GetStarted";
 import Footer from "./components/Footer";
 
 export default function LandingPage() {
+  const router = useRouter();
   return (
     <div className="relative text-white font-sans overflow-x-hidden antialiased selection:bg-[#f97815] selection:text-white">
       {/* Animated Background */}
@@ -55,7 +57,7 @@ export default function LandingPage() {
             </p>
             <div className="flex flex-col sm:flex-row items-center justify-center gap-4">
               <button 
-                onClick={() => window.location.href = "/dashboard"}
+                onClick={() => router.push("/dashboard")}
                 className="w-full sm:w-auto h-14 px-10 rounded-lg bg-[#f97815] hover:bg-[#e0650a] text-[#181411] text-lg font-bold transition-all shadow-[0_0_20px_rgba(249,120,21,0.5)]"
               >
                 Start Free