feat: finish remaining inbound protocols (models, completions, native /route)

- GET /v1/models: pool + virtual cortiq-auto
- POST /v1/completions (legacy): non-stream + streaming text_completion
- POST /route: native passthrough returning the routing decision
- all inbound protocol adapters now implemented; admin meta + README/CHANGELOG updated
- bump to 0.2.1

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/protocols/openai_models.rs

@@ -0,0 +1,32 @@
+//! Inbound OpenAI Models adapter: `GET /v1/models`.
+//! Lists the configured pool (plus the virtual `cortiq-auto`) for client discovery.
+
+use crate::error::{GatewayError, Result};
+use crate::state::SharedState;
+use axum::{extract::State, response::IntoResponse, routing::get, Json, Router};
+
+pub fn routes() -> Router<SharedState> {
+    Router::new().route("/v1/models", get(handler))
+}
+
+async fn handler(State(state): State<SharedState>) -> Result<impl IntoResponse> {
+    let live = state.live();
+    if !live.cfg.protocols.openai_models {
+        return Err(GatewayError::InvalidRequest(
+            "openai_models protocol is disabled".into(),
+        ));
+    }
+    let mut data = vec![serde_json::json!({
+        "id": "cortiq-auto",
+        "object": "model",
+        "owned_by": "cortiq",
+    })];
+    for m in &live.cfg.models {
+        data.push(serde_json::json!({
+            "id": m.id,
+            "object": "model",
+            "owned_by": m.provider,
+        }));
+    }
+    Ok(Json(serde_json::json!({ "object": "list", "data": data })))
+}