feat(openrouter): wire Pareto Code router with min_coding_score knob (#22838)

Pick openrouter/pareto-code as your model and OpenRouter auto-routes each
request to the cheapest model meeting your coding-quality bar (ranked by
Artificial Analysis). The new openrouter.min_coding_score config key (0.0-1.0,
default 0.65) tunes the floor.

- hermes_cli/models.py: add openrouter/pareto-code to OPENROUTER_MODELS so
  it shows up in the picker with a description
- hermes_cli/config.py: add openrouter.min_coding_score (default 0.65 — lands
  on a mid-tier coder on the current Pareto frontier)
- plugins/model-providers/openrouter: emit extra_body.plugins =
  [{id: pareto-router, min_coding_score: X}] when model is openrouter/pareto-code
  AND the score is a valid float in [0.0, 1.0]
- agent/transports/chat_completions.py: same emission on the legacy flag
  path (when no provider profile is loaded)
- run_agent.py: openrouter_min_coding_score kwarg + storage; plumbed into
  both build_kwargs() invocations and the context-summary extra_body path
- cli.py: read openrouter.min_coding_score once at init, validate float in
  [0,1], pass to AIAgent constructions (CLI + background-task paths)
- cron/scheduler.py, batch_runner.py, tools/delegate_tool.py,
  tui_gateway/server.py: propagate the kwarg (mirrors providers_order
  plumbing — subagents inherit, cron/batch read from config)
- tests: profile-level + transport-level coverage of the model gating,
  unset/empty/out-of-range handling, and the legacy flag path
- docs: new 'OpenRouter Pareto Code Router' section in providers.md

Verified end-to-end against api.openrouter.ai: at score=0.65 we land on a
mid-tier coder, at omission we get the strongest. Score is silently dropped
on any model other than openrouter/pareto-code, so it's safe to leave set.

tools/delegate_tool.py

@@ -1077,11 +1077,15 @@ def _build_child_agent(
     child_providers_ignored = getattr(parent_agent, "providers_ignored", None)
     child_providers_order = getattr(parent_agent, "providers_order", None)
     child_provider_sort = getattr(parent_agent, "provider_sort", None)
+    child_openrouter_min_coding_score = getattr(parent_agent, "openrouter_min_coding_score", None)
     if override_provider:
         child_providers_allowed = None
         child_providers_ignored = None
         child_providers_order = None
         child_provider_sort = None
+        # Note: openrouter_min_coding_score is model-gated (only emitted on
+        # openrouter/pareto-code), so we keep it inherited even when the
+        # provider is overridden — it's a no-op on any other model.
 
     child = AIAgent(
         base_url=effective_base_url,
@@ -1111,6 +1115,7 @@ def _build_child_agent(
         providers_ignored=child_providers_ignored,
         providers_order=child_providers_order,
         provider_sort=child_provider_sort,
+        openrouter_min_coding_score=child_openrouter_min_coding_score,
         tool_progress_callback=child_progress_cb,
         iteration_budget=None,  # fresh budget per subagent
     )