fix(openai): strict OpenAI wire compatibility — Open WebUI can chat again

/v1/chat/completions answered ordinary client payloads with a bare HTTP 422
(a plain-text body no OpenAI client can parse), so Open WebUI showed neither
an answer nor an error — it just hung. Parse the body leniently instead:
content as string/null/content-part array, tools: null, stream: null, a
string reasoning_effort, max_completion_tokens, messages[].name and
tool_call_id, and a missing Content-Type. Unreadable bodies now come back as
an OpenAI error envelope with 400.

Responses are strict OpenAI JSON: no "tool_calls": null, finish_reason mapped
to the spec's closed set (cortiq serve's max_tokens -> length), never an empty
id, and `model` echoes the id the client requested — the model that actually
answered stays in cortiq.selected_model and X-Cortiq-Selected-Model.

Streaming is re-normalised rather than forwarded verbatim: a leading role
delta, message-shaped chunks converted to delta, one terminal finish_reason,
always a trailing data: [DONE], and an SSE error event when the upstream dies
mid-flight. Adds X-Accel-Buffering: no so a fronting proxy cannot buffer the
stream into a hang.

GET /v1/models now lists managed [[cmf.servers]] models with their live
running/healthy state, so clients can pin a local .cmf directly.

Also strips client bookkeeping keys (chat_id, session_id, metadata, features,
...) from the upstream call and drops the leftover [to_wire] debug prints.

src/protocols/openai_models.rs

@@ -1,5 +1,10 @@
 //! Inbound OpenAI Models adapter: `GET /v1/models`.
-//! Lists the configured pool (plus the virtual `cortiq-auto`) for client discovery.
+//! Lists everything a client can address: the virtual `cortiq-auto`, the
+//! configured `[[models]]` pool, and the managed local `[[cmf.servers]]`.
+//!
+//! The managed CMF servers belong here because they are routable model ids like
+//! any other — omitting them left OpenAI clients (Open WebUI among them) unable
+//! to pin a local model even though the gateway would happily serve it.
 
 use crate::error::{GatewayError, Result};
 use crate::state::SharedState;
@@ -9,6 +14,13 @@ pub fn routes() -> Router<SharedState> {
     Router::new().route("/v1/models", get(handler))
 }
 
+fn now_secs() -> u64 {
+    std::time::SystemTime::now()
+        .duration_since(std::time::UNIX_EPOCH)
+        .unwrap_or_default()
+        .as_secs()
+}
+
 async fn handler(State(state): State<SharedState>) -> Result<impl IntoResponse> {
     let live = state.live();
     if !live.cfg.protocols.openai_models {
@@ -16,17 +28,51 @@ async fn handler(State(state): State<SharedState>) -> Result<impl IntoResponse>
             "openai_models protocol is disabled".into(),
         ));
     }
+    let created = now_secs();
     let mut data = vec![serde_json::json!({
         "id": "cortiq-auto",
         "object": "model",
+        "created": created,
         "owned_by": "cortiq",
     })];
+    let mut seen: std::collections::HashSet<String> =
+        std::collections::HashSet::from(["cortiq-auto".to_string()]);
+
     for m in &live.cfg.models {
+        if !seen.insert(m.id.clone()) {
+            continue;
+        }
         data.push(serde_json::json!({
             "id": m.id,
             "object": "model",
+            "created": created,
             "owned_by": m.provider,
         }));
     }
+
+    // Managed local CMF servers. Health is reported alongside (a non-standard
+    // field clients ignore) rather than used as a filter: a large `.cmf` takes
+    // minutes to load, and a model that vanishes from the list while it warms up
+    // is worse than one marked "not ready yet".
+    let cmf = state.cmf.status();
+    for s in live.cfg.cmf.effective_servers() {
+        if !seen.insert(s.id.clone()) {
+            continue; // a static [[models]] entry with the same id wins
+        }
+        let status = cmf.servers.iter().find(|st| st.id == s.id);
+        data.push(serde_json::json!({
+            "id": s.id,
+            "object": "model",
+            "created": created,
+            "owned_by": "cortiq-cmf",
+            "cortiq": {
+                "kind": "cmf",
+                "local": true,
+                "running": status.map(|st| st.running).unwrap_or(false),
+                "healthy": status.map(|st| st.healthy).unwrap_or(false),
+            },
+        }));
+    }
+
     Ok(Json(serde_json::json!({ "object": "list", "data": data })))
 }