terms: per-term installer visibility toggles + universal delete (v0.3.4)

- _meta.json: customLabels -> terms.{label,showInInstaller,showInInstallerRp}
- Drop builtin protection; any term kind can be deleted/added/toggled
- New public route /manifest/terms/<pack>/index.json for installer term lists
- Installers fetch terms:list dynamically; skip agreement step if list empty
- Term editor: 2 visibility checkboxes (설치기 / 리소스팩 설치기), multi-select
- Migration from old schema preserves custom labels (default: visible in both)

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

views/op/termsEditor.ejs

@@ -29,6 +29,19 @@
       <span class="statusText" id="status"></span>
     </div>
 
+    <!-- 표시 대상 토글: 어느 인스톨러에서 이 약관을 보여줄지 (중복 선택 가능). -->
+    <fieldset class="termsVisibility" style="margin-top:16px; padding:10px 14px; border:1px solid var(--border, #30363d); border-radius:8px;">
+      <legend style="padding:0 6px; font-size:12px; color:var(--text-muted);"><%= t('terms.visibilityHeading') %></legend>
+      <label style="display:inline-flex; align-items:center; gap:6px; margin-right:18px;">
+        <input type="checkbox" id="visInstaller" <%= showInInstaller ? 'checked' : '' %> />
+        <span><%= t('terms.visibilityInstaller') %></span>
+      </label>
+      <label style="display:inline-flex; align-items:center; gap:6px;">
+        <input type="checkbox" id="visInstallerRp" <%= showInInstallerRp ? 'checked' : '' %> />
+        <span><%= t('terms.visibilityInstallerRp') %></span>
+      </label>
+    </fieldset>
+
     <p class="muted" style="font-size:12px;"><%= t('terms.slashHint') %></p>
 
     <div id="editorWrap" class="termsEditorWrap">