fix(doctor): add missing baseUrl and models when migrating nano-banana apiKey to google provider

The legacy nano-banana-pro skill migration moves the Gemini API key to
models.providers.google.apiKey but does not populate the required baseUrl
and models fields on the provider entry. When the google provider object
is freshly created (no pre-existing config), the resulting config fails
Zod validation on write:

  Config validation failed: models.providers.google.baseUrl:
  Invalid input: expected string, received undefined

Fix: default baseUrl to 'https://generativelanguage.googleapis.com' and
models to [] when they are not already set, matching the defaults used
elsewhere in the codebase (embeddings-gemini, pdf-native-providers).

Fixes the 'doctor --fix' crash for users who only have a legacy
nano-banana-pro skill entry and no existing models.providers.google.

src/commands/doctor-legacy-config.migrations.test.ts

@@ -318,6 +318,10 @@ describe("normalizeCompatibilityConfigValues", () => {
       provider: "default",
       id: "GEMINI_API_KEY",
     });
+    expect(res.config.models?.providers?.google?.baseUrl).toBe(
+      "https://generativelanguage.googleapis.com",
+    );
+    expect(res.config.models?.providers?.google?.models).toEqual([]);
     expect(res.config.skills?.entries).toBeUndefined();
     expect(res.changes).toEqual([
       "Moved skills.entries.nano-banana-pro → agents.defaults.imageGenerationModel.primary (google/gemini-3-pro-image-preview).",
@@ -341,6 +345,10 @@ describe("normalizeCompatibilityConfigValues", () => {
     });
 
     expect(res.config.models?.providers?.google?.apiKey).toBe("env-gemini-key");
+    expect(res.config.models?.providers?.google?.baseUrl).toBe(
+      "https://generativelanguage.googleapis.com",
+    );
+    expect(res.config.models?.providers?.google?.models).toEqual([]);
     expect(res.changes).toContain(
       "Moved skills.entries.nano-banana-pro.env.GEMINI_API_KEY → models.providers.google.apiKey.",
     );

src/commands/doctor-legacy-config.ts

@@ -579,6 +579,12 @@ export function normalizeCompatibilityConfigValues(cfg: OpenClawConfig): {
     const hasGoogleApiKey = rawGoogle.apiKey !== undefined;
     if (!hasGoogleApiKey && legacyApiKey) {
       rawGoogle.apiKey = legacyApiKey;
+      if (!rawGoogle.baseUrl) {
+        rawGoogle.baseUrl = "https://generativelanguage.googleapis.com";
+      }
+      if (!Array.isArray(rawGoogle.models)) {
+        rawGoogle.models = [];
+      }
       rawProviders.google = rawGoogle;
       rawModels.providers = rawProviders as NonNullable<OpenClawConfig["models"]>["providers"];
       next = {