fix(picker): remove max_models=50 cap in interactive model pickers

The interactive model pickers (Desktop REST API, TUI model.options, CLI
/model) were hard-capped at max_models=50, which truncated large provider
catalogs like Kilo Gateway (336 models) to just 50 entries. This made
most models undiscoverable via the picker search box.

Changes:
- Change build_models_payload() default from max_models=50 to None (unlimited)
- Change list_authenticated_providers() default from max_models=8 to None
- Change list_picker_providers() default from max_models=8 to None
- Fix all [:max_models] slicing to handle None as 'no limit'
- Remove max_models=50 from 5 interactive picker callers:
  * web_server.py: get_model_options (Desktop /api/model/options)
  * web_server.py: get_recommended_default_model
  * model_switch.py: prewarm_picker_cache_async
  * tui_gateway/server.py: model.options JSON-RPC
  * cli.py: HermesCLI model picker
- Telegram/Discord inline keyboard picker (gateway/slash_commands.py)
  still passes max_models=50 explicitly — unchanged behavior.

The total_models field was already in the response payload and is now
meaningful since models.length == total_models for interactive pickers.

Fixes #48279

hermes_cli/model_switch.py

@@ -1188,7 +1188,6 @@ def prewarm_picker_cache_async() -> Optional["_threading.Thread"]:
                 current_model=ctx.current_model,
                 user_providers=ctx.user_providers,
                 custom_providers=ctx.custom_providers,
-                max_models=50,
             )
         except Exception:
             # Best-effort warmup — never surface errors into the session.
@@ -1206,7 +1205,7 @@ def list_authenticated_providers(
     custom_providers: list | None = None,
     *,
     force_fresh_nous_tier: bool = False,
-    max_models: int = 8,
+    max_models: int | None = None,
     current_model: str = "",
 ) -> List[dict]:
     """Detect which providers have credentials and list their curated models.
@@ -1426,7 +1425,7 @@ def list_authenticated_providers(
             if hermes_id in _MODELS_DEV_PREFERRED:
                 model_ids = _merge_with_models_dev(hermes_id, model_ids)
         total = len(model_ids)
-        top = model_ids[:max_models]
+        top = model_ids[:max_models] if max_models else model_ids
 
         slug = hermes_id
         pinfo = _mdev_pinfo(mdev_id)
@@ -1589,7 +1588,7 @@ def list_authenticated_providers(
                 if hermes_slug in _MODELS_DEV_PREFERRED:
                     model_ids = _merge_with_models_dev(hermes_slug, model_ids)
         total = len(model_ids)
-        top = model_ids[:max_models]
+        top = model_ids[:max_models] if max_models else model_ids
 
         results.append({
             "slug": hermes_slug,
@@ -1664,7 +1663,7 @@ def list_authenticated_providers(
             if not _cp_model_ids:
                 _cp_model_ids = curated.get(_cp.slug, [])
         _cp_total = len(_cp_model_ids)
-        _cp_top = _cp_model_ids[:max_models]
+        _cp_top = _cp_model_ids[:max_models] if max_models else _cp_model_ids
 
         results.append({
             "slug": _cp.slug,
@@ -2040,7 +2039,7 @@ def list_picker_providers(
     current_base_url: str = "",
     user_providers: dict = None,
     custom_providers: list | None = None,
-    max_models: int = 8,
+    max_models: int | None = None,
     current_model: str = "",
 ) -> List[dict]:
     """Interactive-picker variant of :func:`list_authenticated_providers`.
@@ -2083,7 +2082,7 @@ def list_picker_providers(
             except Exception:
                 live_ids = list(p.get("models", []))
             p = dict(p)
-            p["models"] = live_ids[:max_models]
+            p["models"] = live_ids[:max_models] if max_models else live_ids
             p["total_models"] = len(live_ids)
 
         has_models = bool(p.get("models"))