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/lib/auth.ts

@@ -35,8 +35,8 @@ export const authConfig: NextAuthConfig = {
       // see: https://stackoverflow.com/questions/70409219/get-user-id-from-session-in-next-auth-client
       jwt({ token, account, user }) {
          if (account) {
-            // console.log("(jwt) account:", account);
-            // console.log("(jwt) user:", user);
+            // console.log("(JWT) account:", account);
+            // console.log("(JWT) user:", user);
            token.accessToken = account.access_token;
            // attach Google account ID to the token
            token.piggyback_providerAccountId = account.providerAccountId;
@@ -51,7 +51,7 @@ export const authConfig: NextAuthConfig = {
          if(session.user && token) {
             // assign Google account ID from the token to the Session user ID
             session.user.id = token.piggyback_providerAccountId;
-            // console.log("(jwt) token:", token);
+//            console.log("(SESSION) token:", token);
          }
          return session;
        },