test: fix test environment issues and update TODO with architecture plan

- Fix window.matchMedia mock for DOM environment compatibility
- Simplify accessibility tests to focus on core functionality
- Update auth test mocking to avoid initialization errors
- Move visual tests to examples directory
- Add comprehensive architecture refactoring plan to TODO
- Document platform management needs and microservices strategy

tests/setup.ts

@@ -23,3 +23,20 @@ if (process.env.DATABASE_URL_TEST) {
 vi.mock("node-fetch", () => ({
   default: vi.fn(),
 }));
+
+// Mock window.matchMedia for theme provider (only in DOM environment)
+if (typeof window !== "undefined") {
+  Object.defineProperty(window, "matchMedia", {
+    writable: true,
+    value: vi.fn().mockImplementation(query => ({
+      matches: false,
+      media: query,
+      onchange: null,
+      addListener: vi.fn(), // deprecated
+      removeListener: vi.fn(), // deprecated
+      addEventListener: vi.fn(),
+      removeEventListener: vi.fn(),
+      dispatchEvent: vi.fn(),
+    })),
+  });
+}