fix(ui): detect VS Code from bootstrap config in shared runtime helpers

d2efa707 fixed projects-store detection via __VSCODE_CONFIG__, but
lib/desktop.isVSCodeRuntime (used by useDirectoryStore) still required
RuntimeAPIs. At webview startup that left directory init on stale
localStorage paths from other windows (#2359).

Share bootstrap detection in lib/vscodeBootstrap and use it from both
desktop runtime checks and the projects-store helper.

Co-authored-by: Serhii Dziupin <makeittech@users.noreply.github.com>

packages/ui/src/lib/desktop.vscodeRuntime.test.ts

@@ -0,0 +1,46 @@
+import { afterEach, describe, expect, mock, test } from 'bun:test';
+
+type RuntimeApisStub = { runtime?: { isVSCode?: boolean } } | null;
+
+let registeredRuntimeApis: RuntimeApisStub = null;
+
+mock.module('@/contexts/runtimeAPIRegistry', () => ({
+  getRegisteredRuntimeAPIs: (): RuntimeApisStub => registeredRuntimeApis,
+}));
+
+const { isVSCodeRuntime } = await import('./desktop');
+
+describe('desktop isVSCodeRuntime bootstrap detection', () => {
+  afterEach(() => {
+    registeredRuntimeApis = null;
+    delete (globalThis as { window?: unknown }).window;
+  });
+
+  test('detects VS Code from bootstrap config before RuntimeAPIs register', () => {
+    registeredRuntimeApis = null;
+    (globalThis as { window: unknown }).window = {
+      __VSCODE_CONFIG__: {
+        workspaceFolder: '/Users/me/project-a',
+        workspaceFolders: [{ name: 'project-a', path: '/Users/me/project-a' }],
+      },
+    };
+
+    expect(isVSCodeRuntime()).toBe(true);
+  });
+
+  test('falls back to registered RuntimeAPIs when bootstrap is absent', () => {
+    registeredRuntimeApis = {
+      runtime: { isVSCode: true },
+    };
+    (globalThis as { window: unknown }).window = {};
+
+    expect(isVSCodeRuntime()).toBe(true);
+  });
+
+  test('does not classify an unregistered web runtime as VS Code', () => {
+    registeredRuntimeApis = null;
+    (globalThis as { window: unknown }).window = {};
+
+    expect(isVSCodeRuntime()).toBe(false);
+  });
+});