refactor(auth): separate auth and author responsibilities and centralize auth client creation

- Replace manual axios auth client with createApiClient in auth context
- Decouple domain author logic from auth provider
- Make AuthorModel extend AuthUser explicitly
- Route login/register/logout exclusively through auth package
- Derive application-level currentUser from auth identity
- Fix provider hierarchy and hook usage across Blog and Profile
- Align main.jsx to use base AuthProvider + AuthorProvider layering

auth/src/contexts.tsx

@@ -1,7 +1,6 @@
 import React, { createContext, useContext, useEffect, useState } from "react";
-import axios from "axios";
 import { tokenStore } from "./token";
-import { attachAuthInterceptors } from "./axios";
+import { createApiClient } from "./axios";
 import { AuthUser } from "./models";
 
 interface AuthContextModel {
@@ -19,23 +18,16 @@ const AuthContext = createContext<AuthContextModel | undefined>(undefined);
 export function AuthProvider({
   children,
   authBaseUrl,
-  apiClient,
 }: {
   children: React.ReactNode;
   authBaseUrl: string;
-  apiClient: any; // your domain api client
 }) {
   const [currentUser, setCurrentUser] = useState<AuthUser | null>(null);
   const [token, setToken] = useState<string | null>(tokenStore.get());
   const [loading, setLoading] = useState(false);
   const [error, setError] = useState<string | null>(null);
 
-  const auth = axios.create({
-    baseURL: authBaseUrl,
-    headers: { "Content-Type": "application/json" },
-  });
-
-  attachAuthInterceptors(auth);
+  const auth = createApiClient(authBaseUrl);
 
   const login = async (username: string, password: string) => {
     try {
@@ -61,7 +53,6 @@ export function AuthProvider({
       setError(null);
 
       await auth.post("/register", { username, password });
-      await apiClient.post("/authors", { name: null, avatar: null });
     } catch (e: any) {
       setError(e.response?.data?.detail ?? "Registration failed");
     } finally {
@@ -79,8 +70,7 @@ export function AuthProvider({
     if (!token) return;
     try {
       const me = await auth.get("/me");
-      const author = await apiClient.get("/authors/me");
-      setCurrentUser({ ...me.data, ...author.data });
+      setCurrentUser({ ...me.data });
     } catch {
       logout();
     }

auth/src/index.ts

@@ -1,5 +1,6 @@
-export { AuthProvider, useAuth } from "./context";
+export { AuthProvider, useAuth } from "./contexts";
 export { createApiClient } from "./axios";
 export { AuthPage } from "./AuthPage";
+export type { AuthUser } from "./models";
 export type { AuthMode } from "./AuthPage";
 export { tokenStore } from "./token"