Reader: visible text selection in every theme; highlights follow across translations

Selection
- Selected text uses a per-theme colour (it was nearly invisible on Dark)
- The colour picker also appears on touch screens after dragging the selection
  handles, and sits below the selection there so the system menu doesn't cover it

Highlights
- Each highlight remembers its translation and whether it covers the whole verse
- In another translation the same words are found again (ignoring case and
  punctuation); whole-verse highlights cover the whole verse; when the wording
  differs, the verse gets a small colour dot instead of marking the wrong words
- Older highlights are checked against their saved words instead of trusted
- Server keeps the new fields

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

server/readerMarks.test.js

@@ -58,3 +58,15 @@ test('the database keeps one row per user and updatedAt only moves forward', asy
   expect(saved.highlights).toHaveLength(1);
   expect(db.getReaderMarks('u2').updatedAt).toBe(0); // other users are untouched
 });
+
+test('a highlight keeps the translation it was made in and whether it covers the whole verse', async () => {
+  const { cleanMarks } = await import('./readerMarks.js');
+  const base = { id: 'a', book: 'JHN', chapter: 3, verse: 16, startOffset: 0, endOffset: 40, color: '#fef08a', text: 'For God so loved' };
+  const out = cleanMarks({ highlights: [
+    { ...base, translation: 'BSB', whole: true },
+    { ...base, id: 'b', translation: 'not a code!!', whole: 'yes' },
+  ] }).highlights;
+  expect(out[0]).toMatchObject({ translation: 'BSB', whole: true });
+  expect(out[1].translation).toBeUndefined();
+  expect(out[1].whole).toBeUndefined();
+});