feat(ui): external dictionary lookup link on the word-check tool

When a checked word is found, show a 'look it up' text link beside the
complaint button that opens an external reference dictionary in a new tab:
gramota.ru for the Russian variants, scrabblewordfinder.org for English
(word lower-cased and percent-encoded). The link hides for a word that is
not found. Inside Telegram it routes through the Mini App SDK's openLink, so
Telegram opens it directly instead of the WebView's 'open this link?'
confirmation; in a browser the anchor's own target=_blank handles it.

Relabel the complaint button to 'Возражаю' (ru); English stays 'Disagree'.

ui/src/lib/checkword.test.ts

@@ -1,5 +1,5 @@
 import { describe, expect, it } from 'vitest';
-import { canCheckWord, MAX_WORD_LEN, sanitizeCheckWord } from './checkword';
+import { canCheckWord, dictionaryLookupUrl, MAX_WORD_LEN, sanitizeCheckWord } from './checkword';
 
 const EN = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'.split('');
 
@@ -40,3 +40,18 @@ describe('canCheckWord', () => {
     expect(canCheckWord('  a  ', false, false)).toBe(false);
   });
 });
+
+describe('dictionaryLookupUrl', () => {
+  it('points the Russian variants at gramota.ru with a lower-cased, encoded query', () => {
+    expect(dictionaryLookupUrl('КОТ', 'scrabble_ru')).toBe(
+      'https://gramota.ru/poisk?query=' + encodeURIComponent('кот'),
+    );
+    expect(dictionaryLookupUrl('ЭРА', 'erudit_ru')).toBe(
+      'https://gramota.ru/poisk?query=' + encodeURIComponent('эра'),
+    );
+  });
+
+  it('points English at scrabblewordfinder.org with a lower-cased path', () => {
+    expect(dictionaryLookupUrl('CAT', 'scrabble_en')).toBe('https://scrabblewordfinder.org/dictionary/cat');
+  });
+});