feat(media): implement integrated media manager with sidebar and picker

- Implement DriveService and ShopifyMediaService for backend operations
- Create MediaSidebar.html with premium UI and auto-polling
- Integrate Google Picker API for robust file selection
- Orchestrate sync logic via MediaService (Drive -> Staged Upload -> Shopify)
- Add secure config handling for API keys and tokens
- Update ppsscript.json with required OAuth scopes
- Update MEMORY.md and README.md with architecture details

src/services/DriveService.test.ts

@@ -0,0 +1,30 @@
+import { MockDriveService } from "./MockDriveService"
+
+describe("DriveService", () => {
+  let service: MockDriveService
+
+  beforeEach(() => {
+    service = new MockDriveService()
+  })
+
+  test("getOrCreateFolder creates new folder if not exists", () => {
+    const folder = service.getOrCreateFolder("TestSKU", "root_id")
+    expect(folder.getName()).toBe("TestSKU")
+    expect(folder.getId()).toContain("TestSKU")
+  })
+
+  test("saveFile stores file in correct folder", () => {
+    const folder = service.getOrCreateFolder("TestSKU", "root_id")
+    const mockBlob = {
+        getName: () => "test.jpg",
+        getContentType: () => "image/jpeg"
+    } as unknown as GoogleAppsScript.Base.Blob
+
+    const file = service.saveFile(mockBlob, folder.getId())
+    expect(file.getName()).toBe("test.jpg")
+
+    const files = service.getFiles(folder.getId())
+    expect(files.length).toBe(1)
+    expect(files[0].getId()).toBe(file.getId())
+  })
+})