Add user stats feature with API and modal integration

Introduced an endpoint to fetch user stats and integrated it with a new StatsModal component in the frontend. Users can now view game statistics, including played games, wins, losses, and win rates, accessible from the user menu.

frontend/src/components/StatsModal.jsx

@@ -0,0 +1,101 @@
+import React from "react";
+import { createPortal } from "react-dom";
+import { styles } from "../styles/styles";
+import { stylesTokens } from "../styles/theme";
+
+function Tile({ label, value, sub }) {
+  return (
+    <div
+      style={{
+        borderRadius: 16,
+        border: `1px solid rgba(233,216,166,0.16)`,
+        background: "rgba(10,10,12,0.55)",
+        padding: 12,
+        boxShadow: "inset 0 1px 0 rgba(255,255,255,0.06)",
+      }}
+    >
+      <div
+        style={{
+          fontSize: 11,
+          opacity: 0.8,
+          color: stylesTokens.textDim,
+          letterSpacing: 0.6,
+          textTransform: "uppercase",
+        }}
+      >
+        {label}
+      </div>
+
+      <div
+        style={{
+          marginTop: 6,
+          fontWeight: 1000,
+          fontSize: 26,
+          lineHeight: "30px",
+          color: stylesTokens.textGold,
+        }}
+      >
+        {value}
+      </div>
+
+      {sub ? (
+        <div style={{ marginTop: 2, fontSize: 12, opacity: 0.85, color: stylesTokens.textDim }}>
+          {sub}
+        </div>
+      ) : null}
+    </div>
+  );
+}
+
+export default function StatsModal({ open, onClose, me, stats, loading, error }) {
+  if (!open) return null;
+
+  const displayName = me ? ((me.display_name || "").trim() || me.email) : "";
+
+  return createPortal(
+    <div style={styles.modalOverlay} onMouseDown={onClose}>
+      <div style={styles.modalCard} onMouseDown={(e) => e.stopPropagation()}>
+        <div style={styles.modalHeader}>
+          <div>
+            <div style={{ fontWeight: 1000, color: stylesTokens.textGold }}>Statistik</div>
+            <div style={{ fontSize: 12, opacity: 0.8, color: stylesTokens.textDim }}>
+              {displayName}
+            </div>
+          </div>
+
+          <button onClick={onClose} style={styles.modalCloseBtn} aria-label="Schließen">
+            ✕
+          </button>
+        </div>
+
+        <div style={{ marginTop: 12 }}>
+          {loading ? (
+            <div style={{ padding: 10, color: stylesTokens.textDim, opacity: 0.9 }}>
+              Lade Statistik…
+            </div>
+          ) : error ? (
+            <div style={{ padding: 10, color: "#ffb3b3" }}>{error}</div>
+          ) : (
+            <div
+              style={{
+                display: "grid",
+                gridTemplateColumns: "1fr 1fr",
+                gap: 10,
+              }}
+            >
+              <Tile label="Gespielte Spiele" value={stats?.played ?? 0} />
+              <Tile label="Siege" value={stats?.wins ?? 0} />
+              <Tile label="Verluste" value={stats?.losses ?? 0} />
+              <Tile label="Siegerate" value={`${stats?.winrate ?? 0}%`} sub="nur beendete Spiele" />
+            </div>
+          )}
+        </div>
+
+        <div style={{ marginTop: 12, fontSize: 12, opacity: 0.75, color: stylesTokens.textDim }}>
+          Hinweis: „Gespielt“ zählt nur Spiele mit gesetztem Sieger.
+        </div>
+      </div>
+    </div>,
+    document.body
+  );
+}

frontend/src/components/TopBar.jsx

@@ -8,19 +8,16 @@ export default function TopBar({
   setUserMenuOpen,
   openPwModal,
   openDesignModal,
+  openStatsModal,
   doLogout,
   onOpenNewGame,
 }) {
-  const displayName = me
-    ? ((me.display_name || "").trim() || me.email)
-    : "";
+  const displayName = me ? ((me.display_name || "").trim() || me.email) : "";
 
   return (
     <div style={styles.topBar}>
       <div>
-        <div style={{ fontWeight: 900, color: stylesTokens.textGold }}>
-          Notizbogen
-        </div>
+        <div style={{ fontWeight: 900, color: stylesTokens.textGold }}>Notizbogen</div>
         <div style={{ fontSize: 12, opacity: 0.8, color: stylesTokens.textDim }}>
           {displayName}
         </div>
@@ -52,6 +49,18 @@ export default function TopBar({
                 {me?.email || ""}
               </div>
 
+              <button
+                onClick={() => {
+                  setUserMenuOpen(false);
+                  openStatsModal?.();
+                }}
+                style={styles.userDropdownItem}
+              >
+                Statistik
+              </button>
+
+              <div style={styles.userDropdownDivider} />
+
               <button onClick={openPwModal} style={styles.userDropdownItem}>
                 Passwort setzen
               </button>

frontend/src/components/WinnerBadge.jsx

@@ -49,7 +49,7 @@ export default function WinnerBadge({ winner, winnerEmail }) {
 
           {showEmail && (
             <div style={{ fontSize: 12, opacity: 0.8, color: stylesTokens.textDim }}>
-              {winner.displayName}
+              {winner.display_name}
             </div>
           )}
         </div>

frontend/src/components/WinnerCard.jsx

@@ -25,7 +25,7 @@ export default function WinnerCard({
             <option value="">— kein Sieger —</option>
             {members.map((m) => (
               <option key={m.id} value={m.id}>
-                {m.email}
+                {m.display_name}
               </option>
             ))}
           </select>