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/gateway/test_fast_command.py

@@ -4,7 +4,7 @@ import sys
 import threading
 import types
 from types import SimpleNamespace
-from unittest.mock import AsyncMock, patch
+from unittest.mock import AsyncMock
 
 import pytest
 import yaml
@@ -53,7 +53,6 @@ def _make_runner():
     runner._service_tier = None
     runner._provider_routing = {}
     runner._fallback_model = None
-    runner._smart_model_routing = {}
     runner._running_agents = {}
     runner._pending_model_notes = {}
     runner._session_db = None
@@ -97,13 +96,7 @@ def test_turn_route_injects_priority_processing_without_changing_runtime():
         "credential_pool": None,
     }
 
-    with patch("agent.smart_model_routing.resolve_turn_route", return_value={
-        "model": "gpt-5.4",
-        "runtime": dict(runtime_kwargs),
-        "label": None,
-        "signature": ("gpt-5.4", "openrouter", "https://openrouter.ai/api/v1", "chat_completions", None, ()),
-    }):
-        route = gateway_run.GatewayRunner._resolve_turn_agent_config(runner, "hi", "gpt-5.4", runtime_kwargs)
+    route = gateway_run.GatewayRunner._resolve_turn_agent_config(runner, "hi", "gpt-5.4", runtime_kwargs)
 
     assert route["runtime"]["provider"] == "openrouter"
     assert route["runtime"]["api_mode"] == "chat_completions"
@@ -123,13 +116,7 @@ def test_turn_route_skips_priority_processing_for_unsupported_models():
         "credential_pool": None,
     }
 
-    with patch("agent.smart_model_routing.resolve_turn_route", return_value={
-        "model": "gpt-5.3-codex",
-        "runtime": dict(runtime_kwargs),
-        "label": None,
-        "signature": ("gpt-5.3-codex", "openrouter", "https://openrouter.ai/api/v1", "chat_completions", None, ()),
-    }):
-        route = gateway_run.GatewayRunner._resolve_turn_agent_config(runner, "hi", "gpt-5.3-codex", runtime_kwargs)
+    route = gateway_run.GatewayRunner._resolve_turn_agent_config(runner, "hi", "gpt-5.3-codex", runtime_kwargs)
 
     assert route["request_overrides"] is None