fix: old workspace migration (#14403)

fix #14395 

#### PR Dependency Tree


* **PR #14403** 👈

This tree was auto-generated by
[Charcoal](https://github.com/danerwilliams/charcoal)

<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit

* **New Features**
  * Added ability to enumerate and list local workspaces.
* Improved workspace ID persistence with Electron global-state storage,
automatic fallback to legacy storage, and one-time migration to
consolidate IDs.
* **Tests**
* Added unit test validating listing behavior (includes/excludes
workspaces based on presence of workspace DB file).
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

packages/frontend/apps/electron/test/workspace/handlers.spec.ts

@@ -33,6 +33,43 @@ afterAll(() => {
 });
 
 describe('workspace db management', () => {
+  test('list local workspace ids', async () => {
+    const { listLocalWorkspaceIds } =
+      await import('@affine/electron/helper/workspace/handlers');
+    const validWorkspaceId = v4();
+    const noDbWorkspaceId = v4();
+    const fileEntry = 'README.txt';
+
+    const validWorkspacePath = path.join(
+      appDataPath,
+      'workspaces',
+      'local',
+      validWorkspaceId
+    );
+    const noDbWorkspacePath = path.join(
+      appDataPath,
+      'workspaces',
+      'local',
+      noDbWorkspaceId
+    );
+    const nonDirectoryPath = path.join(
+      appDataPath,
+      'workspaces',
+      'local',
+      fileEntry
+    );
+
+    await fs.ensureDir(validWorkspacePath);
+    await fs.ensureFile(path.join(validWorkspacePath, 'storage.db'));
+    await fs.ensureDir(noDbWorkspacePath);
+    await fs.outputFile(nonDirectoryPath, 'not-a-workspace');
+
+    const ids = await listLocalWorkspaceIds();
+    expect(ids).toContain(validWorkspaceId);
+    expect(ids).not.toContain(noDbWorkspaceId);
+    expect(ids).not.toContain(fileEntry);
+  });
+
   test('trash workspace', async () => {
     const { trashWorkspace } =
       await import('@affine/electron/helper/workspace/handlers');