feat(desktop): persist auxiliary reasoning_effort through the models router

Backend half of the per-task effort control, on today's layout: POST /api/model/set
distinguishes omitted (leave the task's override alone) from explicit null (clear →
inherit) via model_fields_set, canonicalises a level through parse_reasoning_effort
(400 on an unknown one), and "Reset all to main" also drops every override. GET
/api/model/auxiliary returns reasoning_effort per task and the row summary shows it.

The inherit row reads "inherit · main model effort" (own i18n key in all six locales)
rather than reusing the provider's "auto · use main model" copy — the two mean
different things and the reused string read as "use the main model" for the effort.

Runtime already consumes auxiliary.<task>.reasoning_effort (agent/auxiliary_client.py)
and hermes model writes the same key (#110346), so Desktop and CLI now edit one value.

Closes #89259. Salvages #90649 by @higgs1729.

hermes_cli/web_server_config.py

@@ -685,7 +685,26 @@ def _apply_main_assignment_sync(cfg: dict, provider: str, model: str, base_url:
     }
 
 
-def _apply_aux_assignment_sync(cfg: dict, provider: str, model: str, task: str, base_url: str, api_key: str) -> dict:
+# "Field omitted" sentinel for optional assignment fields whose None means "clear".
+_UNSET: Any = object()
+
+
+def _normalize_aux_reasoning_effort(value: Optional[str]) -> Optional[str]:
+    """``auxiliary.<task>.reasoning_effort`` value for an assignment: None clears (inherit), else the
+    canonical level (``none`` for a disable), 400 on an unknown level."""
+    if value is None:
+        return None
+    from hermes_constants import parse_reasoning_effort
+    parsed = parse_reasoning_effort(value)
+    if parsed is None:
+        from hermes_constants import VALID_REASONING_EFFORTS
+        raise HTTPException(status_code=400,
+                            detail=f"reasoning_effort must be one of: none, {', '.join(VALID_REASONING_EFFORTS)}")
+    return "none" if parsed.get("enabled") is False else parsed["effort"]
+
+
+def _apply_aux_assignment_sync(cfg: dict, provider: str, model: str, task: str, base_url: str, api_key: str,
+                               reasoning_effort: Optional[str] = _UNSET) -> dict:
     from hermes_cli.config import save_config
     aux = cfg.get("auxiliary")
     if not isinstance(aux, dict):
@@ -695,12 +714,15 @@ def _apply_aux_assignment_sync(cfg: dict, provider: str, model: str, task: str,
         slot_cfg = aux.get(slot)
         return slot_cfg if isinstance(slot_cfg, dict) else {}
 
+    effort = _normalize_aux_reasoning_effort(reasoning_effort) if reasoning_effort is not _UNSET else _UNSET
+
     if task == "__reset__":
-        # Reset every slot to provider="auto", model="" — keeps other fields intact.
+        # Reset every slot to provider="auto", model="", no effort override — keeps other fields intact.
         for slot in _AUX_TASK_SLOTS:
             slot_cfg = _slot(slot)
             slot_cfg["provider"] = "auto"
             slot_cfg["model"] = ""
+            slot_cfg.pop("reasoning_effort", None)
             slot_cfg.pop("base_url", None)
             clear_model_endpoint_credentials(slot_cfg)
             aux[slot] = slot_cfg
@@ -734,15 +756,23 @@ def _apply_aux_assignment_sync(cfg: dict, provider: str, model: str, task: str,
         elif new_provider != prev_provider and new_provider != "custom":
             slot_cfg.pop("base_url", None)
             clear_model_endpoint_credentials(slot_cfg)
+        if effort is None:
+            slot_cfg.pop("reasoning_effort", None)
+        elif effort is not _UNSET:
+            slot_cfg["reasoning_effort"] = effort
         aux[slot] = slot_cfg
 
     cfg["auxiliary"] = aux
     save_config(cfg)
-    return {"ok": True, "scope": "auxiliary", "tasks": targets, "provider": provider, "model": model}
+    result = {"ok": True, "scope": "auxiliary", "tasks": targets, "provider": provider, "model": model}
+    if effort is not _UNSET:
+        result["reasoning_effort"] = effort
+    return result
 
 
 def _apply_model_assignment_sync(
-    scope: str, provider: str, model: str, task: str, base_url: str, api_key: str = ""
+    scope: str, provider: str, model: str, task: str, base_url: str, api_key: str = "",
+    reasoning_effort: Optional[str] = _UNSET,
 ):
     """Synchronous body of POST /api/model/set.
 
@@ -753,7 +783,7 @@ def _apply_model_assignment_sync(
     cfg = load_config()
     if scope == "main":
         return _apply_main_assignment_sync(cfg, provider, model, base_url, api_key)
-    return _apply_aux_assignment_sync(cfg, provider, model, task, base_url, api_key)
+    return _apply_aux_assignment_sync(cfg, provider, model, task, base_url, api_key, reasoning_effort)
 
 
 def _infer_provider_on_model_change(model_val: str, prev_provider: str) -> tuple[str, str]: