refactor: remove smart_model_routing feature (#12732)

Smart model routing (auto-routing short/simple turns to a cheap model
across providers) was opt-in and disabled by default.  This removes the
feature wholesale: the routing module, its config keys, docs, tests, and
the orchestration scaffolding it required in cli.py / gateway/run.py /
cron/scheduler.py.

The /fast (Priority Processing / Anthropic fast mode) feature kept its
hooks into _resolve_turn_agent_config — those still build a route dict
and attach request_overrides when the model supports it; the route now
just always uses the session's primary model/provider rather than
running prompts through choose_cheap_model_route() first.

Also removed:
- DEFAULT_CONFIG['smart_model_routing'] block and matching commented-out
  example sections in hermes_cli/config.py and cli-config.yaml.example
- _load_smart_model_routing() / self._smart_model_routing on GatewayRunner
- self._smart_model_routing / self._active_agent_route_signature on
  HermesCLI (signature kept; just no longer initialised through the
  smart-routing pipeline)
- route_label parameter on HermesCLI._init_agent (only set by smart
  routing; never read elsewhere)
- 'Smart Model Routing' section in website/docs/integrations/providers.md
- tip in hermes_cli/tips.py
- entries in hermes_cli/dump.py + hermes_cli/web_server.py
- row in skills/autonomous-ai-agents/hermes-agent/SKILL.md

Tests:
- Deleted tests/agent/test_smart_model_routing.py
- Rewrote tests/agent/test_credential_pool_routing.py to target the
  simplified _resolve_turn_agent_config directly (preserves credential
  pool propagation + 429 rotation coverage)
- Dropped 'cheap model' test from test_cli_provider_resolution.py
- Dropped resolve_turn_route patches from cli + gateway test_fast_command
  — they now exercise the real method end-to-end
- Removed _smart_model_routing stub assignments from gateway/cron test
  helpers

Targeted suites: 74/74 in the directly affected test files;
tests/agent + tests/cron + tests/cli pass except 5 failures that
already exist on main (cron silent-delivery + alias quick-command).

tests/cli/test_cli_provider_resolution.py

@@ -207,48 +207,11 @@ def test_cli_turn_routing_uses_primary_when_disabled(monkeypatch):
     shell.api_mode = "chat_completions"
     shell.base_url = "https://openrouter.ai/api/v1"
     shell.api_key = "sk-primary"
-    shell._smart_model_routing = {"enabled": False}
 
     result = shell._resolve_turn_agent_config("what time is it in tokyo?")
 
     assert result["model"] == "gpt-5"
     assert result["runtime"]["provider"] == "openrouter"
-    assert result["label"] is None
-
-
-def test_cli_turn_routing_uses_cheap_model_when_simple(monkeypatch):
-    cli = _import_cli()
-
-    def _runtime_resolve(**kwargs):
-        assert kwargs["requested"] == "zai"
-        return {
-            "provider": "zai",
-            "api_mode": "chat_completions",
-            "base_url": "https://open.z.ai/api/v1",
-            "api_key": "cheap-key",
-            "source": "env/config",
-        }
-
-    monkeypatch.setattr("hermes_cli.runtime_provider.resolve_runtime_provider", _runtime_resolve)
-
-    shell = cli.HermesCLI(model="anthropic/claude-sonnet-4", compact=True, max_turns=1)
-    shell.provider = "openrouter"
-    shell.api_mode = "chat_completions"
-    shell.base_url = "https://openrouter.ai/api/v1"
-    shell.api_key = "primary-key"
-    shell._smart_model_routing = {
-        "enabled": True,
-        "cheap_model": {"provider": "zai", "model": "glm-5-air"},
-        "max_simple_chars": 160,
-        "max_simple_words": 28,
-    }
-
-    result = shell._resolve_turn_agent_config("what time is it in tokyo?")
-
-    assert result["model"] == "glm-5-air"
-    assert result["runtime"]["provider"] == "zai"
-    assert result["runtime"]["api_key"] == "cheap-key"
-    assert result["label"] is not None
 
 
 def test_cli_prefers_config_provider_over_stale_env_override(monkeypatch):