feat: auto-promote free Moonshot models to top of ai-gateway picker

When the live Vercel AI Gateway catalog exposes a Moonshot model with
zero input AND output pricing, it's promoted to position #1 as the
recommended default — even if the exact ID isn't in the curated
AI_GATEWAY_MODELS list. This enables dynamic discovery of new free
Moonshot variants without requiring a PR to update curation.

Paid Moonshot models are unaffected; falls back to the normal curated
recommended tag when no free Moonshot is live.

hermes_cli/models.py

@@ -812,8 +812,24 @@ def fetch_ai_gateway_models(
     if not curated:
         return list(_ai_gateway_catalog_cache or fallback)
 
-    first_id, _ = curated[0]
-    curated[0] = (first_id, "recommended")
+    # If the live catalog offers a free Moonshot model, auto-promote it to
+    # position #1 as "recommended" — dynamic discovery without a PR.
+    free_moonshot = next(
+        (
+            mid
+            for mid, item in live_by_id.items()
+            if mid.startswith("moonshotai/")
+            and _ai_gateway_model_is_free(item.get("pricing"))
+        ),
+        None,
+    )
+    if free_moonshot:
+        curated = [(mid, desc) for mid, desc in curated if mid != free_moonshot]
+        curated.insert(0, (free_moonshot, "recommended"))
+    else:
+        first_id, _ = curated[0]
+        curated[0] = (first_id, "recommended")
+
     _ai_gateway_catalog_cache = curated
     return list(curated)