fix(qoder): allow qmodel_latest model key

- Add qmodel_latest to QODER_MODEL_MAP
- Expose qmodel_latest in static Qoder provider catalog (qd)
- Generalize executor comment so model set does not go stale
- Add unit coverage for the new model key + catalog

Closes #1638

Co-authored-by: Cursor <cursoragent@cursor.com>

open-sse/config/providerModels.js

@@ -153,6 +153,7 @@ export const PROVIDER_MODELS = {
     { id: "lite", name: "Qoder Lite" },
     // Frontier models — pin a specific backing model
     { id: "qmodel", name: "Qwen 3.6 Plus (Qoder)" },
+    { id: "qmodel_latest", name: "Qoder Qwen 3.7 Max" },
     { id: "dmodel", name: "DeepSeek V4 Pro (Qoder)" },
     { id: "dfmodel", name: "DeepSeek V4 Flash (Qoder)" },
     { id: "gm51model", name: "GLM 5.1 (Qoder)" },