fix: custom endpoint provider shows as openrouter in gateway

Three issues caused the gateway to display 'openrouter' instead of
'Custom endpoint' when users configured a custom OAI-compatible endpoint:

1. hermes setup: custom endpoint path saved OPENAI_BASE_URL and
   OPENAI_API_KEY to .env but never wrote model.provider to config.yaml.
   All other providers (Codex, z.ai, Kimi, etc.) call
   _update_config_for_provider() which sets this — custom was the only
   path that skipped it. Now writes model.provider='custom' and
   model.base_url to config.yaml.

2. hermes model: custom endpoint set model.provider='auto' in config.yaml.
   The CLI display had a hack to detect OPENAI_BASE_URL and override to
   'custom', but the gateway didn't. Now sets model.provider='custom'
   directly.

3. gateway /model and /provider commands: defaulted to 'openrouter' and
   read config.yaml — which had no provider set. Added OPENAI_BASE_URL
   detection fallback (same pattern the CLI uses) as a defensive catch
   for existing users who set up before this fix.

gateway/run.py

@@ -1449,6 +1449,11 @@ class GatewayRunner:
             except Exception:
                 current_provider = "openrouter"
 
+        # Detect custom endpoint: provider resolved to openrouter but a custom
+        # base URL is configured — the user set up a custom endpoint.
+        if current_provider == "openrouter" and os.getenv("OPENAI_BASE_URL", "").strip():
+            current_provider = "custom"
+
         if not args:
             provider_label = _PROVIDER_LABELS.get(current_provider, current_provider)
             lines = [
@@ -1575,6 +1580,10 @@ class GatewayRunner:
             except Exception:
                 current_provider = "openrouter"
 
+        # Detect custom endpoint
+        if current_provider == "openrouter" and os.getenv("OPENAI_BASE_URL", "").strip():
+            current_provider = "custom"
+
         current_label = _PROVIDER_LABELS.get(current_provider, current_provider)
 
         lines = [