refactor(responsive): Phase 3 코드 품질 개선

- Blog/BlogMarketing/Subscription/MusicStudio: 미사용 useIsMobile 제거
- Subscription: 미사용 Link import 제거
- Blog.css: 중복 display:block 제거
- BlogMarketing: dead prop onGenerate 제거
- Todo: 카드 버튼 터치 타겟 26→36px 확대

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/pages/blog-marketing/BlogMarketing.jsx

@@ -1,5 +1,4 @@
 import React, { useState, useEffect, useCallback, useRef } from 'react';
-import { useIsMobile } from '../../hooks/useIsMobile';
 import PullToRefresh from '../../components/PullToRefresh';
 import FAB from '../../components/FAB';
 import {
@@ -84,7 +83,6 @@ function usePollTask(onDone) {
 
 /* ══════════════════════════════════════════════════════════════════════════ */
 export default function BlogMarketing() {
-  const isMobile = useIsMobile();
   const [tab, setTab] = useState('dashboard');
   const [status, setStatus] = useState(null);
 
@@ -133,7 +131,7 @@ export default function BlogMarketing() {
       </nav>
 
       {tab === 'dashboard' && <DashboardTab />}
-      {tab === 'research' && <ResearchTab onGenerate={(id) => { setTab('write'); }} />}
+      {tab === 'research' && <ResearchTab />}
       {tab === 'write' && <WriteTab />}
       {tab === 'posts' && <PostsTab />}
 

src/pages/blog/Blog.css

@@ -472,7 +472,6 @@
     }
 
     .blog-list.is-visible {
-        display: block;
         position: fixed;
         top: 0;
         left: 0;

src/pages/blog/Blog.jsx

@@ -6,7 +6,6 @@ import {
     updateBlogPost,
     deleteBlogPost,
 } from '../../api';
-import { useIsMobile } from '../../hooks/useIsMobile';
 import PullToRefresh from '../../components/PullToRefresh';
 import FAB from '../../components/FAB';
 import './Blog.css';
@@ -356,7 +355,6 @@ const BlogEditor = ({ post, onSave, onClose }) => {
 // ── 메인 Blog 컴포넌트 ───────────────────────────────────────────────────────
 
 const Blog = () => {
-    const isMobile = useIsMobile();
     const staticPosts = useMemo(() => getBlogPosts(), []);
     const [apiPosts, setApiPosts] = useState([]);
     const [apiError, setApiError] = useState(false);

src/pages/music/MusicStudio.jsx

@@ -16,7 +16,6 @@ import {
     generateStyleBoost,
     generateVideo,
 } from '../../api';
-import { useIsMobile } from '../../hooks/useIsMobile';
 import PullToRefresh from '../../components/PullToRefresh';
 import FAB from '../../components/FAB';
 import './MusicStudio.css';
@@ -515,7 +514,6 @@ const Library = ({ tracks, onDelete, onRefresh, onExtend, onVocalRemoval, onCove
 ───────────────────────────────────────────── */
 export default function MusicStudio() {
     /* ── 탭 ── */
-    const isMobile = useIsMobile();
     const [tab, setTab] = useState('create');
 
     /* ── Provider 상태 ── */

src/pages/subscription/Subscription.jsx

@@ -1,7 +1,5 @@
 import React, { useState, useEffect, useMemo, useCallback } from 'react';
-import { Link } from 'react-router-dom';
 import { apiGet, apiPost, apiPut, apiDelete } from '../../api';
-import { useIsMobile } from '../../hooks/useIsMobile';
 import PullToRefresh from '../../components/PullToRefresh';
 import FAB from '../../components/FAB';
 import './Subscription.css';
@@ -1299,7 +1297,6 @@ function ProfileTab() {
 
 // ── Subscription (Main) ──────────────────────────────────────────────────────
 function Subscription() {
-    const isMobile = useIsMobile();
     const [activeTab, setActiveTab] = useState(0);
     const [refreshKey, setRefreshKey] = useState(0);
 

src/pages/todo/Todo.css

@@ -222,8 +222,8 @@
     display: flex;
     align-items: center;
     justify-content: center;
-    width: 26px;
-    height: 26px;
+    width: 36px;
+    height: 36px;
     border-radius: 8px;
     border: 1px solid var(--line);
     background: rgba(255, 255, 255, 0.04);