feat(parser): improve choice validation and completion for flagged arguments

- Added `_check_if_in_choices()` to enforce `choices` validation for all nargs modes,
  including after resolver-based and list-based inputs.
- Enhanced `FalyxCompleter` to quote multi-word completions for better UX.
- Improved completion filtering logic to suppress stale suggestions when flag values
  are already consumed.
- Moved `ArgumentState` and `TLDRExample` to `parser_types.py` for reuse.
- Bumped version to 0.1.72.

falyx/completer.py

@@ -90,7 +90,14 @@ class FalyxCompleter(Completer):
             )
             for suggestion in suggestions:
                 if suggestion.startswith(stub):
-                    yield Completion(suggestion, start_position=-len(stub))
+                    if len(suggestion.split()) > 1:
+                        yield Completion(
+                            f'"{suggestion}"',
+                            start_position=-len(stub),
+                            display=suggestion,
+                        )
+                    else:
+                        yield Completion(suggestion, start_position=-len(stub))
         except Exception:
             return