feat(ui): 검색영역 접이식 정리 + 다크모드 입력 대비·터치타깃 개선

- index: 고도화검색을 <details> 접이식으로(prefill 시 open) → 검색 진입점 위계 정리
- 다크모드 입력 테두리 대비 강화(border rgba(255,255,255,0.26)): login·signup·index·game-detail
- 체크박스 터치타깃 1.15rem(login·signup), summary 44px

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01K3FeMrbtxfTScjrwUukyHD

src/main/webapp/WEB-INF/views/game-detail.jsp

@@ -952,6 +952,10 @@
         border-color: var(--accent);
         box-shadow: 0 0 0 3px rgba(232, 165, 75, 0.18);
       }
+      html[data-theme="dark"] .game-comments__form textarea,
+      html[data-theme="dark"] .game-comments__edit-form textarea {
+        border-color: rgba(255, 255, 255, 0.26);
+      }
 
       /* ── 6축 평가 입력 그리드 ─────────────────────────────── */
       .game-reviews__axes {

src/main/webapp/WEB-INF/views/index.jsp

@@ -265,6 +265,11 @@
       html[data-theme="dark"] .search-form__input {
         background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='20' height='20' fill='none' stroke='%23aaa' stroke-width='2'%3E%3Ccircle cx='8.5' cy='8.5' r='5.5'/%3E%3Cpath d='M12 12l5 5'/%3E%3C/svg%3E");
       }
+      html[data-theme="dark"] .search-form__input,
+      html[data-theme="dark"] .advanced-search__input,
+      html[data-theme="dark"] .advanced-search__select {
+        border-color: rgba(255, 255, 255, 0.26);
+      }
       .search-form__input::placeholder {
         color: var(--text-muted);
       }
@@ -394,6 +399,37 @@
         background: var(--card-bg);
         box-shadow: 0 1px 2px rgba(0, 0, 0, 0.04);
       }
+      .advanced-search__summary {
+        display: flex;
+        align-items: center;
+        gap: 0.5rem;
+        padding: 0.5rem 0.25rem;
+        min-height: 44px;
+        box-sizing: border-box;
+        list-style: none;
+        cursor: pointer;
+        font-size: 0.9375rem;
+        font-weight: 700;
+        color: var(--text-muted);
+        -webkit-tap-highlight-color: transparent;
+      }
+      .advanced-search__summary::-webkit-details-marker { display: none; }
+      .advanced-search__summary::before {
+        content: "▶";
+        font-size: 0.65rem;
+        color: var(--accent);
+        transition: transform 0.2s ease;
+      }
+      details[open] .advanced-search__summary::before {
+        transform: rotate(90deg);
+      }
+      .advanced-search__summary:hover {
+        color: var(--text);
+      }
+      /* details 열렸을 때 form 상단 마진 */
+      details[open] > form.advanced-search-form {
+        margin-top: 0.5rem;
+      }
       .advanced-search__row {
         display: flex;
         flex-wrap: wrap;
@@ -475,6 +511,7 @@
         display: grid;
         grid-template-columns: repeat(2, minmax(0, 1fr));
         gap: 0.625rem;
+        justify-content: center;
       }
       @media (min-width: 480px) {
         .card-grid {
@@ -747,7 +784,12 @@
                 </a>
                 <% } %>
             </div>
-            <form class="advanced-search" role="search" action="<%= ctx %>/games/search" method="get">
+<%
+    boolean advOpen = !searchKeyword.isBlank() || !searchCreator.isBlank() || !"latest".equals(searchSort) || !selectedTagSlugs.isEmpty();
+%>
+            <details class="advanced-search"<%= advOpen ? " open" : "" %>>
+              <summary class="advanced-search__summary">상세 검색</summary>
+              <form class="advanced-search-form" role="search" action="<%= ctx %>/games/search" method="get">
                 <div class="advanced-search__row">
                     <label class="search-form__label" for="adv-keyword">게임 이름·소개 검색</label>
                     <input class="advanced-search__input" type="search" id="adv-keyword" name="keyword" value="<%= escapedSearchKeyword %>" placeholder="게임 이름·소개 검색" autocomplete="off" />
@@ -797,6 +839,7 @@
                 </div>
                 <% } %>
               </form>
+            </details>
             <div class="search-history" id="search-history" hidden>
                 <div class="search-history__head">
                     <span class="search-history__label">최근 검색</span>

src/main/webapp/WEB-INF/views/login.jsp

@@ -120,6 +120,9 @@
         border-color: var(--accent);
         box-shadow: 0 0 0 3px rgba(232, 165, 75, 0.25);
       }
+      html[data-theme="dark"] .auth-field__input {
+        border-color: rgba(255, 255, 255, 0.26);
+      }
       .auth-row {
         display: flex;
         align-items: center;
@@ -135,8 +138,8 @@
         color: var(--text-muted);
       }
       .auth-check input {
-        width: 1rem;
-        height: 1rem;
+        width: 1.15rem;
+        height: 1.15rem;
         accent-color: var(--accent);
       }
       .auth-button {

src/main/webapp/WEB-INF/views/signup.jsp

@@ -120,6 +120,9 @@
         border-color: var(--accent);
         box-shadow: 0 0 0 3px rgba(232, 165, 75, 0.25);
       }
+      html[data-theme="dark"] .auth-field__input {
+        border-color: rgba(255, 255, 255, 0.26);
+      }
       .auth-grid {
         display: grid;
         grid-template-columns: repeat(2, minmax(0, 1fr));
@@ -135,8 +138,8 @@
       }
       .auth-check input {
         flex-shrink: 0;
-        width: 1rem;
-        height: 1rem;
+        width: 1.15rem;
+        height: 1.15rem;
         margin-top: 0.15rem;
         accent-color: var(--accent);
       }