Refactor account page structure and update UI

- Move user settings form to dedicated /account/settings route
- Update PageHeader icon from Settings to AccountCircle for clarity
- Update debug log labels in auth config for better readability

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

app/ui/PageHeader.tsx

@@ -1,7 +1,7 @@
 import Image from "next/image";
 import Link from "next/link";
 import { SelectLanguage } from "./SelectLanguage";
-import Settings from "@mui/icons-material/Settings";
+import AccountCircle from "@mui/icons-material/AccountCircle";
 
 export const PageHeader = () =>
     <div className="navbar bg-base-100 mb-6">
@@ -9,6 +9,6 @@ export const PageHeader = () =>
         <span className="grow">&nbsp;</span>
         <SelectLanguage />
         <Link href="/account/" className="btn btn-ghost btn-circle">
-            <Settings className="w-6 h-6" />
+            <AccountCircle  />
         </Link>
     </div>