test(api): cover Docker runtime proxy path resolution to absolute URL

Adds the test from the earlier invalid-url stash: with the Docker runtime
config (relative /api/gemini), getGeminiApiBaseUrlForSettings must return
an absolute URL resolved against the origin, otherwise the @google/genai
SDK's internal new URL() throws 'Invalid URL'.

Author: yeahhe365

src/services/api/geminiApiBaseUrl.test.ts

@@ -1,11 +1,15 @@
-import { describe, expect, it } from 'vitest';
+import { afterEach, describe, expect, it } from 'vitest';
 import {
   getGeminiApiBaseUrlForSettings,
   getGeminiProxyBaseUrlForSettings,
   resolveConfiguredGeminiBaseUrl,
   resolveLiveClientBaseUrl,
 } from './geminiApiBaseUrl';
 
+const setRuntimeConfig = (config: Record<string, unknown> | undefined) => {
+  (window as Window & { __AMC_RUNTIME_CONFIG__?: Record<string, unknown> }).__AMC_RUNTIME_CONFIG__ = config;
+};
+
 const disabledProxySettings = {
   useCustomApiConfig: true,
   useApiProxy: false,
@@ -64,4 +68,21 @@ describe('geminiApiBaseUrl', () => {
       }),
     ).toBeNull();
   });
+
+  it('resolves the Docker runtime relative proxy path into an absolute URL for the SDK', () => {
+    setRuntimeConfig({
+      serverManagedApi: true,
+      useCustomApiConfig: true,
+      useApiProxy: true,
+      apiProxyUrl: '/api/gemini',
+    });
+
+    // A bare relative path would make the @google/genai SDK throw "Invalid URL"
+    // inside new URL(baseUrl + path). It must be resolved against the origin.
+    expect(getGeminiApiBaseUrlForSettings()).toBe('http://localhost/api/gemini');
+  });
+
+  afterEach(() => {
+    setRuntimeConfig(undefined);
+  });
 });