feat: add --exclude flag to filter out words with specific letters

Added --exclude argument to allow users to exclude words containing any
of the specified letters. This is useful for Wordle gameplay when certain
letters have been ruled out.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

wordle_helper.py

@@ -17,6 +17,11 @@ def main() -> int:
         metavar="LETTERS",
         help="Only include words composed solely of these letters (case-insensitive)",
     )
+    parser.add_argument(
+        "--exclude",
+        metavar="LETTERS",
+        help="Exclude words containing any of these letters (case-insensitive)",
+    )
     parser.add_argument(
         "--mask",
         metavar="PATTERN",
@@ -44,6 +49,7 @@ def main() -> int:
     args = parser.parse_args()
 
     only_set = set(args.only.lower()) if args.only else None
+    exclude_set = set(args.exclude.lower()) if args.exclude else None
 
     # Prepare matchers
     # Validate and normalize mask
@@ -82,6 +88,8 @@ def main() -> int:
     def matches(word: str) -> bool:
         if only_set is not None and not (set(word.lower()) <= only_set):
             return False
+        if exclude_set is not None and (set(word.lower()) & exclude_set):
+            return False
         if mask_positions is not None:
             wl = word.lower()
             for i, ch in enumerate(mask_positions):