fix(model_switch): section 3 base_url/model/dedup follow-up

On top of the salvaged PR #12505 (Jason/farion1231, which adds dict-format
models: enumeration to both sections), three section-3 refinements from
competing PR #11534 (YangManBOBO):

- accept base_url as canonical (matches Hermes's writer and custom_providers
  entries); keep api/url as fallbacks for legacy/hand-edited configs
- accept singular model as a default_model synonym, matching custom_providers
- add seen_slugs guard so the same provider slug appearing in both
  providers: dict and custom_providers: list emits exactly one picker row
  (providers: dict wins since section 3 runs first)

Two regression tests cover the new behavior. AUTHOR_MAP entry added for
farion1231 so CI doesn't reject the cherry-picked commit.

hermes_cli/model_switch.py

@@ -1039,9 +1039,23 @@ def list_authenticated_providers(
         for ep_name, ep_cfg in user_providers.items():
             if not isinstance(ep_cfg, dict):
                 continue
+            # Skip if this slug was already emitted (e.g. canonical provider
+            # with the same name) or will be picked up by section 4.
+            if ep_name.lower() in seen_slugs:
+                continue
             display_name = ep_cfg.get("name", "") or ep_name
-            api_url = ep_cfg.get("api", "") or ep_cfg.get("url", "") or ""
-            default_model = ep_cfg.get("default_model", "")
+            # ``base_url`` is Hermes's canonical write key (matches
+            # custom_providers and _save_custom_provider); ``api`` / ``url``
+            # remain as fallbacks for hand-edited / legacy configs.
+            api_url = (
+                ep_cfg.get("base_url", "")
+                or ep_cfg.get("api", "")
+                or ep_cfg.get("url", "")
+                or ""
+            )
+            # ``default_model`` is the legacy key; ``model`` matches what
+            # custom_providers entries use, so accept either.
+            default_model = ep_cfg.get("default_model", "") or ep_cfg.get("model", "")
 
             # Build models list from both default_model and full models array
             models_list = []
@@ -1073,6 +1087,7 @@ def list_authenticated_providers(
                 "source": "user-config",
                 "api_url": api_url,
             })
+            seen_slugs.add(ep_name.lower())
 
     # --- 4. Saved custom providers from config ---
     # Each ``custom_providers`` entry represents one model under a named