fix: restore frontend source code (src/web/) that was accidentally deleted

Frontend source is needed for development/building the SPA.
Only Node.js runtime server code should be removed.

src/web/pages/accounts.centered-modal.test.ts

@@ -0,0 +1,15 @@
+import { describe, expect, it } from 'vitest';
+import { readFileSync } from 'node:fs';
+import { resolve } from 'node:path';
+
+describe('Accounts centered modal adoption', () => {
+  it('uses CenteredModal for add/edit/rebind flows instead of inline panel cards', () => {
+    const source = readFileSync(resolve(process.cwd(), 'src/web/pages/Accounts.tsx'), 'utf8');
+
+    expect(source).toContain(
+      'import CenteredModal from "../components/CenteredModal.js";',
+    );
+    expect(source).toContain('<CenteredModal');
+    expect(source).not.toContain('className={`card panel-presence rebind-panel');
+  });
+});