test(03-01): add Wave 0 RED baseline stubs for all 7 requirements

- src/App.test.tsx: WIZD-02 step routing (3 stubs)
- src/components/wizard/BackendSelectionStep.test.tsx: WIZD-01, WIZD-04 (10 stubs)
- src/components/wizard/RemoteConfigStep.test.tsx: BACK-01, BACK-02, BACK-03 (8 stubs)
- src/components/wizard/StepIndicator.test.tsx: WIZD-03 (5 stubs)
- All 26 tests fail RED with descriptive 'not yet implemented' messages

src/components/wizard/BackendSelectionStep.test.tsx

@@ -0,0 +1,50 @@
+// @vitest-environment jsdom
+// Covers WIZD-01: card grid renders Azure Blob, Amazon S3, S3-Compatible (Azure first)
+// Covers WIZD-04: remote name field validates alphanumeric/dash/underscore
+import { describe, it, expect } from 'vitest';
+
+describe('BackendSelectionStep', () => {
+  describe('WIZD-01: backend card grid', () => {
+    it('renders Azure Blob Storage card', () => {
+      expect.fail('not yet implemented');
+    });
+
+    it('renders Amazon S3 card', () => {
+      expect.fail('not yet implemented');
+    });
+
+    it('renders S3-Compatible card', () => {
+      expect.fail('not yet implemented');
+    });
+
+    it('Azure Blob is listed before S3 in DOM order', () => {
+      expect.fail('not yet implemented');
+    });
+
+    it('clicking a backend card dispatches SET_BACKEND_TYPE and SET_STEP', () => {
+      expect.fail('not yet implemented');
+    });
+  });
+
+  describe('WIZD-04: remote name field', () => {
+    it('renders remote name input at the top of the step', () => {
+      expect.fail('not yet implemented');
+    });
+
+    it('shows no error before first Next attempt', () => {
+      expect.fail('not yet implemented');
+    });
+
+    it('shows inline error after first Next attempt with invalid name', () => {
+      expect.fail('not yet implemented');
+    });
+
+    it('accepts alphanumeric, dashes, and underscores', () => {
+      expect.fail('not yet implemented');
+    });
+
+    it('rejects names with spaces or special characters', () => {
+      expect.fail('not yet implemented');
+    });
+  });
+});