Refactor authActions module

Refactor authActions.ts into smaller files for better maintainability and readability.

src/contexts/auth/signUp.ts

@@ -0,0 +1,37 @@
+
+import { supabase } from '@/lib/supabase';
+import { handleNetworkError, showAuthToast } from './auth.utils';
+
+export const signUp = async (email: string, password: string, username: string) => {
+  try {
+    console.log('회원가입 시도:', { email, username });
+    
+    const { data, error } = await supabase.auth.signUp({
+      email,
+      password,
+      options: {
+        data: {
+          username,
+        },
+      },
+    });
+
+    if (error) {
+      console.error('회원가입 오류:', error);
+      showAuthToast('회원가입 실패', error.message, 'destructive');
+      return { error, user: null };
+    }
+
+    showAuthToast('회원가입 성공', '이메일 확인 후 로그인해주세요.');
+    
+    return { error: null, user: data.user };
+  } catch (error: any) {
+    console.error('회원가입 중 예외 발생:', error);
+    
+    // 네트워크 오류 확인
+    const errorMessage = handleNetworkError(error);
+    
+    showAuthToast('회원가입 오류', errorMessage, 'destructive');
+    return { error, user: null };
+  }
+};