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.

website/docs/integrations/providers.md

@@ -1372,6 +1372,26 @@ provider_routing:
 
 **Shortcuts:** Append `:nitro` to any model name for throughput sorting (e.g., `anthropic/claude-sonnet-4:nitro`), or `:floor` for price sorting.
 
+## OpenRouter Pareto Code Router
+
+OpenRouter ships an experimental coding-model router at `openrouter/pareto-code` that auto-routes requests to the cheapest model meeting a coding-quality bar (ranked by [Artificial Analysis](https://artificialanalysis.ai/)). Pick this model and tune the `min_coding_score` knob in `~/.hermes/config.yaml`:
+
+```yaml
+model:
+  provider: openrouter
+  model: openrouter/pareto-code
+
+openrouter:
+  min_coding_score: 0.65   # 0.0–1.0; higher = stronger (more expensive) coders. Default 0.65.
+```
+
+Notes:
+
+- `min_coding_score` is **only** sent when `model.model` is `openrouter/pareto-code`. On any other model the value is a no-op.
+- Set to empty string (or remove the line) to let OpenRouter pick the strongest available coder — its documented behavior when the plugins block is omitted.
+- Selection is deterministic per score on a given day, but the actual model chosen can shift as the Pareto frontier moves (new models, benchmark updates).
+- See OpenRouter's [Pareto Router docs](https://openrouter.ai/docs/guides/routing/routers/pareto-router) for the full router behavior.
+
 ## Fallback Model
 
 Configure a backup provider:model that Hermes switches to automatically when your primary model fails (rate limits, server errors, auth failures):