feat: migrate to Next.js for Mini App and enhance project structure

- Replaced the previous webapp with a new Mini App built using Next.js, improving performance and maintainability.
- Updated the `.gitignore` to exclude Next.js build artifacts and node modules.
- Revised documentation in `AGENTS.md`, `README.md`, and `architecture.md` to reflect the new Mini App structure and technology stack.
- Enhanced Dockerfile to support the new build process for the Next.js application.
- Updated CI workflow to build and test the Next.js application.
- Added new configuration options for the Mini App, including `MINI_APP_SHORT_NAME` for improved deep linking.
- Refactored frontend testing setup to accommodate the new structure and testing framework.
- Removed legacy webapp files and dependencies to streamline the project.

webapp-next/src/components/contact/ContactLinks.test.tsx

@@ -0,0 +1,60 @@
+/**
+ * Unit tests for ContactLinks: phone/Telegram display, labels, layout.
+ * Ported from webapp/js/contactHtml.test.js buildContactLinksHtml.
+ */
+
+import { describe, it, expect, beforeEach } from "vitest";
+import { render, screen } from "@testing-library/react";
+import { ContactLinks } from "./ContactLinks";
+import { resetAppStore } from "@/test/test-utils";
+
+describe("ContactLinks", () => {
+  beforeEach(() => {
+    resetAppStore();
+  });
+
+  it("returns null when phone and username are missing", () => {
+    const { container } = render(
+      <ContactLinks phone={null} username={null} />
+    );
+    expect(container.firstChild).toBeNull();
+  });
+
+  it("renders phone only with label and tel: link", () => {
+    render(<ContactLinks phone="+79991234567" username={null} showLabels />);
+    expect(document.querySelector('a[href^="tel:"]')).toBeInTheDocument();
+    expect(screen.getByText(/Phone/i)).toBeInTheDocument();
+  });
+
+  it("displays phone formatted for Russian numbers", () => {
+    render(<ContactLinks phone="79146522209" username={null} />);
+    expect(screen.getByText(/\+7 914 652-22-09/)).toBeInTheDocument();
+  });
+
+  it("renders username only with label and t.me link", () => {
+    render(<ContactLinks phone={null} username="alice_dev" showLabels />);
+    expect(document.querySelector('a[href*="t.me"]')).toBeInTheDocument();
+    expect(screen.getByText(/alice_dev/)).toBeInTheDocument();
+  });
+
+  it("renders both phone and username with labels", () => {
+    render(
+      <ContactLinks
+        phone="+79001112233"
+        username="bob"
+        showLabels
+      />
+    );
+    expect(document.querySelector('a[href^="tel:"]')).toBeInTheDocument();
+    expect(document.querySelector('a[href*="t.me"]')).toBeInTheDocument();
+    expect(screen.getByText(/\+7 900 111-22-33/)).toBeInTheDocument();
+    expect(screen.getByText(/@bob/)).toBeInTheDocument();
+  });
+
+  it("strips leading @ from username and displays with @", () => {
+    render(<ContactLinks phone={null} username="@alice" />);
+    const link = document.querySelector('a[href*="t.me/alice"]');
+    expect(link).toBeInTheDocument();
+    expect(link?.textContent).toContain("@alice");
+  });
+});