fix: /model command — bare provider names, custom endpoint display

Two issues with /model preventing proper provider switching:

1. Bare provider names not detected: typing '/model nous' treated 'nous'
   as a model name instead of triggering a provider switch. Fixed by adding
   step 0 in detect_provider_for_model() that checks if the input matches
   a known provider name/alias (excluding 'custom'/'openrouter' which need
   explicit model names) and returns that provider's default model.

2. Custom endpoint details hidden: /model (no args) showed '[custom]' with
   just a usage hint but no endpoint URL or model name. Now displays the
   configured base_url for custom providers in both CLI and gateway.

Note: config base_url and OPENAI_BASE_URL are intentionally NOT cleared on
provider switch — dedicated provider paths (nous, anthropic, codex) have
their own credential resolution that ignores these, and clearing them would
destroy the user's custom endpoint config, preventing switching back.

Co-authored-by: Test <test@test.com>

hermes_cli/models.py

@@ -389,6 +389,7 @@ def detect_provider_for_model(
     Returns ``None`` when no confident match is found.
 
     Priority:
+    0. Bare provider name → switch to that provider's default model
     1. Direct provider with credentials (highest)
     2. Direct provider without credentials → remap to OpenRouter slug
     3. OpenRouter catalog match
@@ -399,6 +400,21 @@ def detect_provider_for_model(
 
     name_lower = name.lower()
 
+    # --- Step 0: bare provider name typed as model ---
+    # If someone types `/model nous` or `/model anthropic`, treat it as a
+    # provider switch and pick the first model from that provider's catalog.
+    # Skip "custom" and "openrouter" — custom has no model catalog, and
+    # openrouter requires an explicit model name to be useful.
+    resolved_provider = _PROVIDER_ALIASES.get(name_lower, name_lower)
+    if resolved_provider not in {"custom", "openrouter"}:
+        default_models = _PROVIDER_MODELS.get(resolved_provider, [])
+        if (
+            resolved_provider in _PROVIDER_LABELS
+            and default_models
+            and resolved_provider != normalize_provider(current_provider)
+        ):
+            return (resolved_provider, default_models[0])
+
     # Aggregators list other providers' models — never auto-switch TO them
     _AGGREGATORS = {"nous", "openrouter"}