gateway: expose GreenPT's Metis decision model at /v1/systemone

Metis is a decision endpoint (state + typed questions -> probabilities),
not a chat completion: it emits no text, so it cannot be a model_list entry.
Expose it as a pass-through endpoint under general_settings, behind the
member's normal co-op key (auth: true), with GreenPT's key injected from the
app env (Bearer os.environ/GREENPT_API_KEY). cost_per_request is an
APPROXIMATION for budget accounting (~800 input tokens at $0.12/1M);
exact billing would need a patch_*.py in the house style.

config.yaml

@@ -233,6 +233,35 @@ general_settings:
   database_url: os.environ/DATABASE_URL
   store_model_in_db: true
 
+  # --- Metis (GreenPT) — decision model, not a chat model ---
+  # Metis is a *decision* endpoint, not a chat completion: it takes a `state`
+  # plus up to 32 typed questions and returns PROBABILITIES / choices / scores.
+  # It generates no text (output_tokens is always 0), so it cannot be a
+  # model_list entry — LiteLLM's chat pipeline has nothing to parse. It is
+  # exposed as a pass-through route instead, and members call it with their
+  # normal co-op API key (auth: true), never the provider key.
+  #
+  # GreenPT-hosted (policy-based privacy, EU, 100% renewable), same
+  # GREENPT_API_KEY the green chat models already use.
+  #   Price: $0.12 per 1M *input* tokens; output is free.
+  #
+  # METERING IS APPROXIMATE. LiteLLM cannot price a pass-through route from the
+  # response body, so cost_per_request (USD per request) is a flat estimate used
+  # for budget accounting — 0.0001 ≈ a typical ~800-input-token call. Exact
+  # per-token billing (reading usage.input_tokens from the Metis response) would
+  # need a patch in the house style of the existing patch_*.py files; until then
+  # treat the spend figure for this route as an approximation, not an invoice.
+  pass_through_endpoints:
+    - path: "/v1/systemone"
+      target: "https://api.greenpt.ai/v1/systemone"
+      headers:
+        Authorization: "Bearer os.environ/GREENPT_API_KEY"
+        Content-Type: "application/json"
+      auth: true
+      methods: ["POST"]
+      timeout: 60
+      cost_per_request: 0.0001
+
 litellm_settings:
   salt_key: os.environ/LITELLM_SALT_KEY
   drop_params: true