feat(10-02): create RemoteNamePreview component with TDD

- Stateless component accepting value prop (string)
- Empty/whitespace state: shows grayed [my-remote] placeholder + guidance text
- Value state: shows [typed-value] in on-surface-variant color
- Renders only div/span elements — no form controls
- 9 tests covering empty state, value state, and element type constraints

src/components/ui/RemoteNamePreview.test.tsx

@@ -0,0 +1,57 @@
+// @vitest-environment jsdom
+import { describe, it, expect } from 'vitest';
+import { render, screen } from '@testing-library/react';
+import { RemoteNamePreview } from './RemoteNamePreview';
+
+describe('RemoteNamePreview', () => {
+  describe('empty state', () => {
+    it('shows placeholder [my-remote] when value is empty string', () => {
+      render(<RemoteNamePreview value="" />);
+      expect(screen.getByText('[my-remote]')).toBeDefined();
+    });
+
+    it('shows placeholder [my-remote] when value is whitespace-only', () => {
+      render(<RemoteNamePreview value="   " />);
+      expect(screen.getByText('[my-remote]')).toBeDefined();
+    });
+
+    it('shows guidance text when value is empty', () => {
+      render(<RemoteNamePreview value="" />);
+      expect(screen.getByText('Type a name to see how it appears in your config')).toBeDefined();
+    });
+  });
+
+  describe('value state', () => {
+    it('shows [my-backup] when value is "my-backup"', () => {
+      render(<RemoteNamePreview value="my-backup" />);
+      expect(screen.getByText('[my-backup]')).toBeDefined();
+    });
+
+    it('shows [azure-prod] when value is "azure-prod"', () => {
+      render(<RemoteNamePreview value="azure-prod" />);
+      expect(screen.getByText('[azure-prod]')).toBeDefined();
+    });
+
+    it('does NOT show guidance text when value is provided', () => {
+      render(<RemoteNamePreview value="my-backup" />);
+      expect(screen.queryByText('Type a name to see how it appears in your config')).toBeNull();
+    });
+  });
+
+  describe('element types', () => {
+    it('renders no form controls (no textbox role)', () => {
+      render(<RemoteNamePreview value="" />);
+      expect(screen.queryByRole('textbox')).toBeNull();
+    });
+
+    it('renders no input elements', () => {
+      const { container } = render(<RemoteNamePreview value="test" />);
+      expect(container.querySelector('input')).toBeNull();
+    });
+
+    it('renders no textarea elements', () => {
+      const { container } = render(<RemoteNamePreview value="test" />);
+      expect(container.querySelector('textarea')).toBeNull();
+    });
+  });
+});

src/components/ui/RemoteNamePreview.tsx

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+interface RemoteNamePreviewProps {
+  value: string;
+}
+
+export function RemoteNamePreview({ value }: RemoteNamePreviewProps) {
+  const trimmed = value.trim();
+  const isEmpty = trimmed.length === 0;
+
+  return (
+    <div className="mt-2 rounded-md bg-surface-variant px-3 py-2 text-xs font-mono">
+      {isEmpty ? (
+        <>
+          <span className="text-on-surface-variant/50">[my-remote]</span>
+          <p className="mt-1 text-on-surface-variant/40 font-sans">
+            Type a name to see how it appears in your config
+          </p>
+        </>
+      ) : (
+        <span className="text-on-surface-variant">[{trimmed}]</span>
+      )}
+    </div>
+  );
+}