feat: add article list below player

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

index.html

@@ -274,6 +274,52 @@
             margin-top: 4px;
         }
 
+        /* ── 記事リスト ─────────────────────────────────────────────── */
+        .brief-list {
+            flex-shrink: 0;
+            max-height: 38dvh;
+            overflow-y: auto;
+            border-top: 1px solid var(--border);
+            scrollbar-width: none;
+        }
+        .brief-list::-webkit-scrollbar { display: none; }
+        .brief-list-item {
+            display: flex;
+            align-items: flex-start;
+            gap: 12px;
+            padding: 10px 16px;
+            border-bottom: 1px solid var(--border);
+            cursor: pointer;
+            transition: background 0.12s;
+        }
+        .brief-list-item:active { background: var(--surface); }
+        .brief-list-item.active { background: var(--surface); }
+        .brief-list-num {
+            font-size: 11px;
+            color: var(--text3);
+            width: 16px;
+            flex-shrink: 0;
+            padding-top: 2px;
+            font-variant-numeric: tabular-nums;
+        }
+        .brief-list-num.active { color: var(--accent); }
+        .brief-list-info { flex: 1; min-width: 0; }
+        .brief-list-title {
+            font-size: 13px;
+            color: var(--text2);
+            line-height: 1.4;
+            display: -webkit-box;
+            -webkit-line-clamp: 2;
+            -webkit-box-orient: vertical;
+            overflow: hidden;
+        }
+        .brief-list-title.active { color: var(--text); font-weight: 500; }
+        .brief-list-source {
+            font-size: 11px;
+            color: var(--text3);
+            margin-top: 2px;
+        }
+
         /* ── 音声エンジン表示 ───────────────────────────────────────── */
         .voice-badge {
             display: inline-flex;
@@ -391,6 +437,9 @@
         </button>
     </div>
 
+    <!-- 記事リスト -->
+    <div class="brief-list" id="briefList"></div>
+
 </main>
 
 <div id="toast" role="status" aria-live="polite"></div>
@@ -623,6 +672,7 @@ function updateArticleDisplay(a, idx) {
     document.getElementById('briefTitle').textContent   = a.title || '---';
     document.getElementById('briefSource').textContent  = a.source || '';
     document.getElementById('briefProgress').textContent = '';
+    updateListHighlight(idx);
     // MediaSession
     if ('mediaSession' in navigator) {
         navigator.mediaSession.metadata = new MediaMetadata({
@@ -633,6 +683,39 @@ function updateArticleDisplay(a, idx) {
     }
 }
 
+function renderList() {
+    const list = document.getElementById('briefList');
+    list.innerHTML = '';
+    articles.forEach((a, i) => {
+        const item = document.createElement('div');
+        item.className = 'brief-list-item' + (i === currentIdx ? ' active' : '');
+        item.innerHTML = `
+            <span class="brief-list-num${i === currentIdx ? ' active' : ''}">${i + 1}</span>
+            <div class="brief-list-info">
+                <div class="brief-list-title${i === currentIdx ? ' active' : ''}">${a.title || ''}</div>
+                ${a.source ? `<div class="brief-list-source">${a.source}</div>` : ''}
+            </div>`;
+        item.addEventListener('click', () => {
+            const wasPlaying = isPlaying;
+            stopAudio();
+            currentIdx = i;
+            updateArticleDisplay(articles[i], i);
+            if (wasPlaying) { isPlaying = true; updatePlayBtn(); playNext(); }
+        });
+        list.appendChild(item);
+    });
+}
+
+function updateListHighlight(idx) {
+    document.querySelectorAll('.brief-list-item').forEach((el, i) => {
+        const active = i === idx;
+        el.classList.toggle('active', active);
+        el.querySelector('.brief-list-num').classList.toggle('active', active);
+        el.querySelector('.brief-list-title').classList.toggle('active', active);
+        if (active) el.scrollIntoView({ block: 'nearest', behavior: 'smooth' });
+    });
+}
+
 function updateVoiceBadge(isVoicevox) {
     const badge = document.getElementById('voiceBadge');
     const label = document.getElementById('voiceBadgeLabel');
@@ -738,6 +821,7 @@ async function loadFeed() {
 
         document.getElementById('briefCount').textContent = `${list.length}件`;
         updateArticleDisplay(list[0], 0);
+        renderList();
     } catch (e) {
         document.getElementById('briefTitle').textContent  = '記事の取得に失敗しました';
         document.getElementById('briefSource').textContent = 'ネットワークを確認してください';