Revamp questionnaire, parallelize run-all, add new tasks

- Replace 6 compound Likert questions with 12 atomic ones grouped by
  dimension (syntax, expressiveness, data/IO, errors, overall); drop
  free-form question. Responses now stored as ints, not strings.
- Back-compat layer maps legacy keys to new dimensions so existing
  results still render.
- Parallelize run-all with ThreadPoolExecutor (configurable workers)
  and add a thread-safe min-request-interval rate limiter to the
  Anthropic provider.
- Add new tasks: path_normalizer, todo_manager, currency_converter,
  locale_weather_url, network_info_parser, url_normalizer.

lush_bench/config.py

@@ -13,6 +13,7 @@ class Config:
     timeout_seconds: float = 10.0
     normalize_whitespace: bool = True
     output_dir: Path = Path("results")
+    max_workers: int = 4
     provider_configs: dict[str, dict[str, Any]] = field(default_factory=dict)
 
     @classmethod
@@ -35,5 +36,6 @@ class Config:
             timeout_seconds=agent.get("timeout_seconds", 10.0),
             normalize_whitespace=agent.get("normalize_whitespace", True),
             output_dir=Path(results.get("output_dir", "results")),
+            max_workers=agent.get("max_workers", 4),
             provider_configs=provider_configs,
         )