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/shared/components/layouts/AuthLayout.js

@@ -1,5 +1,6 @@
 "use client";
 
+import PropTypes from "prop-types";
 import ThemeToggle from "../ThemeToggle";
 
 export default function AuthLayout({ children }) {
@@ -22,3 +23,7 @@ export default function AuthLayout({ children }) {
   );
 }
 
+AuthLayout.propTypes = {
+  children: PropTypes.node.isRequired,
+};
+