feat: add /api/dashboard endpoint with hero match, stats, streak, nudges

Returns next tippable match (hero), user rank/points from leaderboard,
consecutive-tip streak, and up to 3 contextual nudges in one request.
Mounts at /api/dashboard; adds getDashboard() + DashboardData type to
the frontend API client.

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

frontend/src/api/client.ts

@@ -53,6 +53,9 @@ export const api = {
       body: JSON.stringify({ team }),
     }),
 
+  // Dashboard
+  getDashboard: () => request<DashboardData>('/dashboard'),
+
   // Admin
   syncMatches: () =>
     request<{ success: boolean; total: number; created: number; updated: number }>(
@@ -67,6 +70,24 @@ export const api = {
 };
 
 // Types (gespiegelt vom Backend)
+export interface DashboardData {
+  hero: {
+    match: {
+      id: number;
+      homeTeam: { name: string; shortName: string; crest: string | null };
+      awayTeam: { name: string; shortName: string; crest: string | null };
+      utcDate: string;
+      status: string;
+      minutesUntilKickoff: number;
+    };
+    userTip: { home: number; away: number } | null;
+    tippable: boolean;
+  } | null;
+  stats: { rank: number | null; totalPoints: number; streak: number };
+  nudges: Array<{ type: string; text: string; matchId?: number }>;
+}
+
+
 export interface Match {
   id: number;
   externalId: number;