POL-124: Migrate frontend from React Native to Next.js web app

- Replace mobile/ (Expo) with web/ (Next.js 16 + Tailwind + shadcn/ui)
- Pages: login, register, pending, championships, championship detail, registrations, profile, admin
- Logic/view separated: hooks/ for data, components/ for UI, pages compose both
- Types in src/types/ (one interface per file)
- Auth: Zustand store + localStorage tokens + cookie presence flag for proxy
- API layer: axios client with JWT auto-refresh

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

web/src/lib/tokenStorage.ts

@@ -0,0 +1,60 @@
+const ACCESS_KEY = "access_token";
+const REFRESH_KEY = "refresh_token";
+
+let _accessToken: string | null = null;
+let _refreshToken: string | null = null;
+
+function setCookie(name: string, days: number) {
+  const expires = new Date(Date.now() + days * 864e5).toUTCString();
+  document.cookie = `${name}=1; expires=${expires}; path=/; SameSite=Lax`;
+}
+
+function deleteCookie(name: string) {
+  document.cookie = `${name}=; expires=Thu, 01 Jan 1970 00:00:00 GMT; path=/`;
+}
+
+export function saveTokens(access: string, refresh: string) {
+  _accessToken = access;
+  _refreshToken = refresh;
+  if (typeof window !== "undefined") {
+    localStorage.setItem(ACCESS_KEY, access);
+    localStorage.setItem(REFRESH_KEY, refresh);
+    // Presence-only cookies so Next.js middleware can check auth on the edge
+    setCookie(ACCESS_KEY, 1);
+    setCookie(REFRESH_KEY, 7);
+  }
+}
+
+export function getAccessToken(): string | null {
+  if (_accessToken) return _accessToken;
+  if (typeof window !== "undefined") {
+    _accessToken = localStorage.getItem(ACCESS_KEY);
+  }
+  return _accessToken;
+}
+
+export function getRefreshToken(): string | null {
+  if (_refreshToken) return _refreshToken;
+  if (typeof window !== "undefined") {
+    _refreshToken = localStorage.getItem(REFRESH_KEY);
+  }
+  return _refreshToken;
+}
+
+export function clearTokens() {
+  _accessToken = null;
+  _refreshToken = null;
+  if (typeof window !== "undefined") {
+    localStorage.removeItem(ACCESS_KEY);
+    localStorage.removeItem(REFRESH_KEY);
+    deleteCookie(ACCESS_KEY);
+    deleteCookie(REFRESH_KEY);
+  }
+}
+
+export function loadFromStorage() {
+  if (typeof window !== "undefined") {
+    _accessToken = localStorage.getItem(ACCESS_KEY);
+    _refreshToken = localStorage.getItem(REFRESH_KEY);
+  }
+}