feat: Fortschritts-Tracking – user_daily_activity, Tagesziel & GET /auth/stats

- Neue Tabelle user_daily_activity (Tagesverlauf) + Spalte daily_goal_ep
- POST /auth/progress schreibt Tagesaktivität mit
- GET /auth/me liefert daily_goal_ep
- Neuer GET /auth/stats: Tagesverlauf, Tagesziel, Totals, echte Skills je answer_type
- Neuer PUT /auth/goal zum Setzen des Tagesziels

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/routes/auth.js

@@ -138,6 +138,7 @@ router.get('/me', requireJwt, async (req, res, next) => {
               un.username,
               COALESCE(up.total_ep, 0)    AS total_ep,
               COALESCE(up.streak_days, 0) AS streak_days,
+              COALESCE(up.daily_goal_ep, 30) AS daily_goal_ep,
               up.last_practice_at,
               ln.id AS language_native_id, ln.short_en AS language_native_short, ln.titel_de AS language_native_titel,
               lt.id AS language_target_id, lt.short_en AS language_target_short, lt.titel_de AS language_target_titel
@@ -177,6 +178,17 @@ router.post('/progress', requireJwt, async (req, res, next) => {
       [userId, pair_id, isCorrect ? 1 : 0, isCorrect ? 0 : 1, pts]
     );
 
+    // Tagesverlauf upserten (für Streak-Kalender, Wochengraph, Tagesziel)
+    await query(
+      `INSERT INTO user_daily_activity (user_id, activity_date, ep_earned, cards_done, correct_count)
+       VALUES ($1, CURRENT_DATE, $2, 1, $3)
+       ON CONFLICT (user_id, activity_date) DO UPDATE SET
+         ep_earned     = user_daily_activity.ep_earned + $2,
+         cards_done    = user_daily_activity.cards_done + 1,
+         correct_count = user_daily_activity.correct_count + $3`,
+      [userId, pts, isCorrect ? 1 : 0]
+    );
+
     // EP + Streak auf users_public; Streak: +1 bei neuem Tag, Reset bei Lücke > 1 Tag
     const upd = await query(
       `UPDATE users_public SET
@@ -201,6 +213,98 @@ router.post('/progress', requireJwt, async (req, res, next) => {
   } catch (err) { next(err); }
 });
 
+// GET /auth/stats — Fortschrittsdaten für das Profil (Verlauf, Tagesziel, Skills)
+router.get('/stats', requireJwt, async (req, res, next) => {
+  try {
+    const userId = req.user.userId;
+
+    // Tagesverlauf der letzten ~84 Tage (für Heatmap-Kalender + Wochengraph)
+    const daily = await query(
+      `SELECT to_char(activity_date, 'YYYY-MM-DD') AS date, ep_earned AS ep, cards_done AS cards, correct_count AS correct
+         FROM user_daily_activity
+        WHERE user_id = $1 AND activity_date >= CURRENT_DATE - INTERVAL '83 days'
+        ORDER BY activity_date ASC`,
+      [userId]
+    );
+
+    // Heute (für Tagesziel-Ring) + Tagesziel aus dem Profil
+    const today = await query(
+      `SELECT COALESCE(da.ep_earned, 0) AS ep, COALESCE(da.cards_done, 0) AS cards,
+              COALESCE(up.daily_goal_ep, 30) AS daily_goal_ep
+         FROM users_public up
+         LEFT JOIN user_daily_activity da
+           ON da.user_id = up.user_id AND da.activity_date = CURRENT_DATE
+        WHERE up.user_id = $1`,
+      [userId]
+    );
+
+    // Gesamtstatistik aus user_pair_progress
+    const totals = await query(
+      `SELECT COUNT(*)::int AS pairs_practiced,
+              COALESCE(SUM(seen_count), 0)::int    AS total_seen,
+              COALESCE(SUM(correct_count), 0)::int AS total_correct
+         FROM user_pair_progress
+        WHERE user_id = $1`,
+      [userId]
+    );
+
+    // Skills: echte Genauigkeit je answer_type des Pairs.
+    // Mapping answer_type → Skill-Label: word/question → Vokabular, text → Lesen, yes_no → Verständnis.
+    const skillRows = await query(
+      `SELECT p.answer_type,
+              COALESCE(SUM(upp.correct_count), 0)::int AS correct,
+              COALESCE(SUM(upp.seen_count), 0)::int    AS seen
+         FROM user_pair_progress upp
+         JOIN pairs p ON p.id = upp.pair_id
+        WHERE upp.user_id = $1
+        GROUP BY p.answer_type`,
+      [userId]
+    );
+
+    const SKILL_MAP = { word: 'Vokabular', question: 'Vokabular', text: 'Lesen', yes_no: 'Verständnis' };
+    const skillAcc = {}; // label -> { correct, seen }
+    for (const r of skillRows.rows) {
+      const label = SKILL_MAP[r.answer_type] || 'Sonstige';
+      const acc = (skillAcc[label] ||= { correct: 0, seen: 0 });
+      acc.correct += r.correct;
+      acc.seen += r.seen;
+    }
+    // Feste Reihenfolge, damit der Radar stabil bleibt; value = Genauigkeit (0..1)
+    const skills = ['Vokabular', 'Lesen', 'Verständnis'].map((label) => {
+      const acc = skillAcc[label];
+      return { label, value: acc && acc.seen > 0 ? acc.correct / acc.seen : 0, seen: acc?.seen || 0 };
+    });
+
+    const t = totals.rows[0] || { pairs_practiced: 0, total_seen: 0, total_correct: 0 };
+    const td = today.rows[0] || { ep: 0, cards: 0, daily_goal_ep: 30 };
+
+    res.json({
+      daily: daily.rows,
+      today: { ep: td.ep, cards: td.cards, daily_goal_ep: td.daily_goal_ep },
+      totals: {
+        pairs_practiced: t.pairs_practiced,
+        total_seen: t.total_seen,
+        total_correct: t.total_correct,
+        accuracy: t.total_seen > 0 ? t.total_correct / t.total_seen : 0,
+      },
+      skills,
+    });
+  } catch (err) { next(err); }
+});
+
+// PUT /auth/goal — Tagesziel (EP/Tag) setzen
+router.put('/goal', requireJwt, async (req, res, next) => {
+  try {
+    const goal = Math.max(5, Math.min(500, parseInt(req.body?.daily_goal_ep) || 0));
+    const upd = await query(
+      `UPDATE users_public SET daily_goal_ep = $2 WHERE user_id = $1 RETURNING daily_goal_ep`,
+      [req.user.userId, goal]
+    );
+    if (!upd.rows.length) return res.status(409).json({ error: 'Kein Profil vorhanden.' });
+    res.json({ daily_goal_ep: upd.rows[0].daily_goal_ep });
+  } catch (err) { next(err); }
+});
+
 // POST /auth/profile — one-time profile creation for the authed user
 router.post('/profile', requireJwt, async (req, res, next) => {
   try {