hangman: add retry + log validation failures for word generation

Silent failures (word too long/short, has hyphens, empty hint) are now
logged as warnings showing the actual word/hint returned. Retry up to
2 times before giving up, matching riddle's behavior.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

matrixbot/commands.py

@@ -1390,6 +1390,7 @@ async def _generate_hangman_word() -> dict | None:
         'Format: {"word": "example", "hint": "short category or hint"}'
     )
     user_msg = "Pick a common English word between 5 and 8 letters (lowercase letters only, no hyphens or spaces) and give a short hint."
+    for attempt in range(2):
         try:
             timeout = aiohttp.ClientTimeout(total=60)
             async with aiohttp.ClientSession(timeout=timeout) as session:
@@ -1413,14 +1414,15 @@ async def _generate_hangman_word() -> dict | None:
                     try:
                         parsed = json.loads(candidate)
                     except json.JSONDecodeError:
-                    logger.warning("hangman: JSON parse failed, raw: %.200s", text)
+                        logger.warning("hangman: JSON parse failed (attempt %d), raw: %.200s", attempt + 1, text)
                         parsed = {}
                     word = parsed.get("word", "").lower().strip()
                     hint = parsed.get("hint", "").strip()
                     if word.isalpha() and 5 <= len(word) <= 8 and hint:
                         return {"word": word, "hint": hint}
+                    logger.warning("hangman: validation failed (attempt %d): word=%r hint=%r", attempt + 1, word, hint)
         except Exception as e:
-        logger.error(f"hangman word generation error: {e}", exc_info=True)
+            logger.error(f"hangman word generation error (attempt {attempt + 1}): {e}", exc_info=True)
     return None