feat(config): add subtitle CSS editor, nPlusOne.enabled flag, and fix se

- subtitleStyle.css / subtitleStyle.secondary.css replace flat style fields in the settings window
- ankiConnect.nPlusOne.enabled gates known-word cache independently of knownWords.highlightEnabled
- Settings search now covers all categories, narrows on multi-word terms, and hides editor-owned fields
- Default note-type picker to Kiku then Lapis; rename isLapis.sentenceCardModel default to "Lapis"

src/settings/index.html

@@ -33,7 +33,6 @@
               placeholder="Search"
               aria-label="Search settings"
             />
-            <button id="openFileButton" class="secondary-button" type="button">Open File</button>
             <button id="saveButton" class="primary-button" type="button" disabled>Save</button>
           </div>
         </header>