refactor: integrate Better-Auth for authentication and remove Supabase dependencies

apps/frontend/src/lib/api-client.ts

@@ -29,7 +29,7 @@ import type {
   UserProfileResponse,
 } from '@repo/api-contract';
 import axios, { AxiosError } from 'axios';
-import { createAuthClient } from "better-auth/react";
+import { createAuthClient } from 'better-auth/react';
 
 const apiBaseUrl =
   import.meta.env.VITE_API_BASE_URL?.trim() ||
@@ -37,9 +37,11 @@ const apiBaseUrl =
 
 export const authClient = createAuthClient({
   baseURL: apiBaseUrl,
+  fetchOptions: {
+    credentials: 'include',
+  },
 });
 
-
 export class ApiClientError extends Error {
   status?: number;
   details?: unknown;
@@ -66,6 +68,7 @@ const handlers: ErrorHandlers = {};
 
 const http = axios.create({
   baseURL: apiBaseUrl,
+  withCredentials: true,
   headers: {
     'Content-Type': 'application/json',
   },
@@ -285,6 +288,6 @@ export function configureApiClient(nextHandlers: ErrorHandlers) {
   handlers.onError = nextHandlers.onError;
 }
 
-export function setApiAccessToken(token: string | null) {
+export function setApiAccessToken(_token: string | null) {
   // accessToken = token;
 }