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/settings-markup.test.ts

@@ -0,0 +1,11 @@
+import test from 'node:test';
+import assert from 'node:assert/strict';
+import fs from 'node:fs';
+import path from 'node:path';
+
+test('settings toolbar does not expose an open file button', () => {
+  const html = fs.readFileSync(path.join(process.cwd(), 'src/settings/index.html'), 'utf8');
+
+  assert.equal(html.includes('id="openFileButton"'), false);
+  assert.equal(html.includes('Open File'), false);
+});