chore: prune unused imports and duplicate import redefinitions

Remove unused imports (F401) and duplicate/shadowed import
redefinitions (F811) across the codebase using ruff's safe
autofixes. No behavioral changes -- imports only.

- ~1400 safe autofixes applied across 644 files (net -1072 lines)
- __init__.py re-exports preserved (excluded from F401 removal so
  public re-export surfaces stay intact)
- Re-exports that are imported or monkeypatched by tests but look
  unused in their defining module are kept with explicit # noqa:
  F401 (gateway/run.py load_dotenv; run_agent re-exports from
  agent.message_sanitization, agent.context_compressor,
  agent.retry_utils, agent.prompt_builder, agent.process_bootstrap,
  agent.codex_responses_adapter)
- Unsafe F841 (unused-variable) fixes deliberately skipped -- those
  can change behavior when the RHS has side effects
- ruff lints remain disabled in pyproject.toml (only PLW1514 is
  selected); this is a one-time cleanup, not a config change

Verification:
- python -m compileall: clean
- pytest --collect-only: all 27161 tests collect (zero import errors)
- core entry points import clean (run_agent, model_tools, cli,
  toolsets, hermes_state, batch_runner, gateway)
- static scan: every name any test imports directly from an edited
  module still resolves

tools/web_tools.py

@@ -51,21 +51,9 @@ import httpx  # noqa: F401 — kept at module top so tests can patch tools.web_t
 if TYPE_CHECKING:
     from firecrawl import Firecrawl  # noqa: F401 — type hints only
 from plugins.web.firecrawl.provider import (
-    Firecrawl,
-    _FirecrawlProxy,
-    _FIRECRAWL_CLS_CACHE,
-    _extract_scrape_payload,
-    _extract_web_search_results,
     _firecrawl_backend_help_suffix,
-    _get_direct_firecrawl_config,
-    _get_firecrawl_client,
     _get_firecrawl_gateway_url,
-    _has_direct_firecrawl_config,
     _is_tool_gateway_ready,
-    _load_firecrawl_cls,
-    _normalize_result_list,
-    _raise_web_backend_configuration_error,
-    _to_plain_object,
     check_firecrawl_api_key,
 )
 # Tavily helpers re-exported for backward-compat with existing unit tests
@@ -112,7 +100,6 @@ from tools.tool_backend_helpers import (  # noqa: F401
     prefers_gateway,
 )
 from tools.url_safety import is_safe_url
-from tools.website_policy import check_website_access
 import sys
 
 logger = logging.getLogger(__name__)