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.ts

@@ -3,6 +3,8 @@
 // variant alphabet, the length bounds, the answered-word cache and the cool-down
 // throttle) are unit-testable and stay in lockstep with the UI.
 
+import type { Variant } from './model';
+
 /** The longest word that fits on a standard 15-cell board line. */
 export const MAX_WORD_LEN = 15;
 /** The shortest word worth checking. */
@@ -29,3 +31,16 @@ export function canCheckWord(word: string, alreadyChecked: boolean, cooling: boo
   const w = word.trim();
   return w.length >= MIN_WORD_LEN && w.length <= MAX_WORD_LEN && !alreadyChecked && !cooling;
 }
+
+/**
+ * dictionaryLookupUrl returns the external reference-dictionary search URL for a checked word
+ * in the given variant: gramota.ru for the Russian variants (scrabble_ru, erudit_ru) and
+ * scrabblewordfinder.org for English. The word is lower-cased and percent-encoded, so a
+ * Cyrillic query travels safely.
+ */
+export function dictionaryLookupUrl(word: string, variant: Variant): string {
+  const w = encodeURIComponent(word.toLowerCase());
+  return variant.endsWith('_ru')
+    ? `https://gramota.ru/poisk?query=${w}`
+    : `https://scrabblewordfinder.org/dictionary/${w}`;
+}