fix(ui): lower-case hint preview words to match evaluate

A hint's MoveRecord words are upper-cased on decode (for the move-history view),
whereas an EvalResult keeps the backend's lower case. Seeding the move preview
from the hint verbatim flipped the score caption to upper case and nudged its
height. Lower-case the words in previewFromHint so the caption reads the same
as the evaluate path it replaces.

ui/src/lib/placement.test.ts

@@ -107,7 +107,7 @@ describe('placementFromHint', () => {
 });
 
 describe('previewFromHint', () => {
-  it('reuses the hint move as a legal preview, carrying score, words and direction', () => {
+  it('reuses the hint move as a legal preview, lower-casing words to match evaluate', () => {
     const preview = previewFromHint({
       player: 0,
       action: 'play',
@@ -120,7 +120,7 @@ describe('previewFromHint', () => {
       score: 18,
       total: 42,
     });
-    expect(preview).toEqual({ legal: true, score: 18, words: ['CAT', 'AN'], dir: 'V' });
+    expect(preview).toEqual({ legal: true, score: 18, words: ['cat', 'an'], dir: 'V' });
   });
 });