chore: remove unused imports and dead locals (ruff F401/F841 sweep)

Cleans F401 unused imports and F841 dead local assignments across
root *.py, agent/, hermes_cli/, tools/, gateway/, cron/, tui_gateway/
(tests/, plugins/, skills/ excluded).

Intentionally KEPT (false positives / test-patch surfaces):
- agent/transports/__init__.py package re-exports
- cli.py browser_connect re-exports (DEFAULT_BROWSER_CDP_URL area,
  used by tests/cli/test_cli_browser_connect.py)
- hermes_cli/main.py _prompt_auth_credentials_choice /
  _model_flow_bedrock_api_key (accessed via main_mod attr in tests)
- gateway/run.py aliased replay_cleanup + whatsapp_identity re-exports
  and _PORT_BINDING_PLATFORM_VALUES (test-referenced)
- hermes_cli/web_server.py get_running_pid (tests monkeypatch it) and
  _OAUTH_TOKEN_URL availability probe
- hermes_cli/config.py get_process_hermes_home re-export (noqa'd F811
  chain) and yaml availability-probe import
- hermes_cli/nous_subscription.py managed_nous_tools_enabled
  (tests patch hermes_cli.nous_subscription.managed_nous_tools_enabled)
- try/except ImportError availability probes (env_loader, tts_tool,
  mcp_tool, web_server anthropic OAuth block)
- tools/web_tools.py noqa F401 re-exports
- hermes_cli/setup_whatsapp_cloud.py:263 'proceed' skipped: possible
  missing-guard bug, flagged for separate review
- unused function parameters (signature changes out of scope)

Side-effect RHS calls preserved where only the binding was dead
(e.g. web_server proc = _spawn_hermes_action -> bare call).

cli.py

@@ -50,8 +50,6 @@ logger = logging.getLogger(__name__)
 # Suppress startup messages for clean CLI experience
 os.environ["HERMES_QUIET"] = "1"  # Our own modules
 
-import yaml
-
 from hermes_cli.fallback_config import get_fallback_chain
 from hermes_cli.cli_agent_setup_mixin import CLIAgentSetupMixin
 from hermes_cli.cli_commands_mixin import CLICommandsMixin
@@ -11635,7 +11633,6 @@ class HermesCLI(CLIAgentSetupMixin, CLICommandsMixin, CLIBillingMixin):
             # it must commit at least the same line.
             if function_name and self.tool_progress_mode in {"new", "all", "verbose"}:
                 duration = kwargs.get("duration", 0.0)
-                is_error = kwargs.get("is_error", False)
                 # Pop stored args from tool.started for this function
                 stored = self._pending_tool_info.get(function_name)
                 stored_args = stored.pop(0) if stored else {}