fix(onboarding): drop "Default" sentinel from model picker; auto-select real model

The CEO-runtime model dropdown on the Company onboarding step rendered
a {value:"", label:"默认 / Default"} sentinel as the first option, a
holdover from the adapter era when "" meant "let the connector pick".
Under pi-mono every connector carries a defaultModel and every run
must bind a concrete model id, so the sentinel is now misleading —
picking it left selectedModel empty and the wizard would advance
without a valid model.

- CompanyStep: drop the sentinel from the options array; the dropdown
  now shows only real models (or a single "Loading..." entry while
  the per-connector fetch is in flight).
- useConnectorModelSelection: when the connector's current model is
  not enabled, auto-select the connector's defaultModel if enabled,
  otherwise the first enabled model. An empty enabled list still
  falls back to "" so the CompanyStep hint UI behaves correctly.

Result: Fire Pass now shows "Kimi K2.5 Turbo (Fire Pass)" as the
sole option (pre-selected). Every other connector picks its catalog
default up-front.

typecheck 0 / lint 0-0 / build 0-0 / test:unit 508/508.

src/renderer/components/company-onboarding/CompanyStep.tsx

@@ -71,10 +71,11 @@ export function CompanyStep({ onContinue, onBack }: CompanyStepProps) {
               value={selectedModel}
               onChange={setSelectedModel}
               disabled={loadingModels || modelOptions.length === 0}
-              options={[
-                { value: "", label: loadingModels ? (currentLocale === "zh" ? "加载中..." : "Loading...") : (currentLocale === "zh" ? "默认" : "Default") },
-                ...modelOptions.map((m) => ({ value: m.id, label: m.label })),
-              ]}
+              options={
+                loadingModels
+                  ? [{ value: "", label: currentLocale === "zh" ? "加载中..." : "Loading..." }]
+                  : modelOptions.map((m) => ({ value: m.id, label: m.label }))
+              }
             />
           </div>
           <div className="mt-3 rounded-lg border border-border bg-background/60 px-3 py-2.5 text-[11px] leading-relaxed text-muted-foreground">

src/renderer/components/company-onboarding/useConnectorModelSelection.ts

@@ -128,12 +128,23 @@ export function useConnectorModelSelection(
       setSelectedModel("");
       return;
     }
-    setSelectedModel((currentModel) =>
-      currentModel && connectorModels.some((entry) => entry.enabled && entry.id === currentModel)
-        ? currentModel
-        : "",
-    );
-  }, [connectorModels, selectedConnectorId]);
+    const enabledModels = connectorModels.filter((entry) => entry.enabled);
+    if (enabledModels.length === 0) {
+      setSelectedModel("");
+      return;
+    }
+    setSelectedModel((currentModel) => {
+      if (currentModel && enabledModels.some((entry) => entry.id === currentModel)) {
+        return currentModel;
+      }
+      const connectorDefinition = executionReadyConnectors.find((c) => c.id === selectedConnectorId);
+      const preferred = connectorDefinition?.model;
+      if (preferred && enabledModels.some((entry) => entry.id === preferred)) {
+        return preferred;
+      }
+      return enabledModels[0]?.id ?? "";
+    });
+  }, [connectorModels, selectedConnectorId, executionReadyConnectors]);
 
   const modelOptions = useMemo(
     () => connectorModels