ADD: added initial page with login

frontend/src/pages/api.tsx

@@ -0,0 +1,45 @@
+const API_URL = 'http://localhost:8080/api';
+
+export async function login(email: string, password: string) {
+  const res = await fetch(`${API_URL}/login`, {
+    method: 'POST',
+    headers: { 'Content-Type': 'application/json' },
+    body: JSON.stringify({ email, password }),
+  });
+  if (!res.ok) throw new Error('Login fehlgeschlagen');
+  return res.json(); // { token: string }
+}
+
+export async function fetchTournaments() {
+  const res = await fetch(`${API_URL}/tournaments`);
+  if (!res.ok) throw new Error('Fehler beim Laden der Turniere');
+  return res.json();
+}
+
+export async function fetchTournament(id: string, token?: string) {
+  const res = await fetch(`${API_URL}/tournaments/${id}`, {
+    headers: token ? { Authorization: `Bearer ${token}` } : undefined,
+  });
+  if (!res.ok) throw new Error('Fehler beim Laden des Turniers');
+  return res.json();
+}
+
+export async function updateTournament(id: string, data: any, token: string) {
+  const res = await fetch(`${API_URL}/tournaments/${id}`, {
+    method: 'PUT',
+    headers: { 'Content-Type': 'application/json', Authorization: `Bearer ${token}` },
+    body: JSON.stringify(data),
+  });
+  if (!res.ok) throw new Error('Update fehlgeschlagen');
+  return res.json();
+}
+
+export async function registerTeam(id: string, team: { name: string }, token: string) {
+  const res = await fetch(`${API_URL}/tournaments/${id}/register`, {
+    method: 'POST',
+    headers: { 'Content-Type': 'application/json', Authorization: `Bearer ${token}` },
+    body: JSON.stringify(team),
+  });
+  if (!res.ok) throw new Error('Team-Anmeldung fehlgeschlagen');
+  return res.json();
+}