make streaks and the leaderboard live, and stop three AI chats from freezing the API

Found in a deeper pass over what the frontend's flow actually touches:

- Nothing in the app ever wrote StreakRecord: "days in a row" was 0 forever
  for every real user. Answers and lesson/island completions now record the
  day (Tehran time); a broken chain shows 0. A streak error never fails the
  answer itself.
- /api/leaderboard only changed when someone ran rebuild_leaderboard by
  hand. It is now computed live (60s cache); weekly counts island XP too.
- gunicorn ran 3 sync workers with a 30s timeout, so every "ask Pi" stream
  pinned a whole worker (~10s, GapGPT buffers the answer) and three at once
  queued the entire API. gunicorn.conf.py (read automatically from the
  working directory) switches to gthread, 8 threads, 120s timeout.
- Every /api/ response now says Cache-Control: private, no-store, so turning
  on caching in the ArvanCloud panel can never serve one student another's data.
- /api/user/summary named no active plan ever ("subscription app not
  implemented yet" had long stopped being true).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

progress/views.py

@@ -8,6 +8,7 @@ from rest_framework.throttling import ScopedRateThrottle
 from rest_framework.views import APIView
 
 from .models import Character, LeaderboardEntry, StreakRecord, UserHearts, UserStats
+from .services import effective_current_streak
 
 
 class GuestAwareReadThrottle(ScopedRateThrottle):
@@ -34,6 +35,20 @@ from .serializers import (
 )
 
 
+def _active_plan_title(user_id):
+    from django.db.models import Q
+    from django.utils import timezone
+
+    from subscription.models import Subscription
+    sub = (
+        Subscription.objects.select_related('plan')
+        .filter(user_id=user_id, status='active')
+        .filter(Q(expires_at__isnull=True) | Q(expires_at__gt=timezone.now()))
+        .first()
+    )
+    return sub.plan.title if sub and sub.plan else None
+
+
 class UserSummaryView(APIView):
     """GET /api/user/summary — پروفایل + آمار + استریک (ادغام‌شده)"""
 
@@ -55,11 +70,12 @@ class UserSummaryView(APIView):
             'xp': stats.xp if stats else 0,
             'coins': stats.coins if stats else 0,
             'streak': {
-                'current': streak.current_streak if streak else 0,
+                'current': effective_current_streak(streak),
                 'longest': streak.longest_streak if streak else 0,
             },
-            # اپ subscription هنوز در این فاز پیاده‌سازی نشده؛ فعلاً null.
-            'subscription': None,
+            # عنوانِ پلنِ اشتراکِ فعال، یا null. تا ۲۰۲۶-۰۹-۲۴ همیشه null بود
+            # (از زمانی که اپِ subscription هنوز وجود نداشت).
+            'subscription': _active_plan_title(user.id),
         }
         return Response(UserSummaryResponseSerializer(data).data)
 
@@ -77,13 +93,18 @@ class StreakCalendarView(APIView):
         streak = StreakRecord.objects.filter(user_id=user.id).first()
 
         data = {
-            'currentStreak': streak.current_streak if streak else 0,
+            'currentStreak': effective_current_streak(streak),
             'longestStreak': streak.longest_streak if streak else 0,
             'activeDays': list(streak.active_days.values_list('date', flat=True)) if streak else [],
         }
         return Response(StreakCalendarResponseSerializer(data).data)
 
 
+# کوتاه تا XPی تازه زود دیده شود، بلند تا هزار کاربرِ هم‌زمان هر بار جدول را
+# از نو حساب نکنند.
+LEADERBOARD_CACHE_TTL = 60
+
+
 class LeaderboardView(APIView):
     """GET /api/leaderboard?period= — رتبه‌بندی هفتگی/ماهانه"""
 
@@ -98,7 +119,20 @@ class LeaderboardView(APIView):
     )
     def get(self, request):
         period = request.query_params.get('period', 'weekly')
-        entries = LeaderboardEntry.objects.filter(period=period).order_by('rank')[:50]
+
+        # زنده از فعالیتِ واقعی، با کشِ کوتاه (progress/leaderboard.py). قبلاً از
+        # جدولِ LeaderboardEntry خوانده می‌شد که فقط با اجرای دستیِ
+        # rebuild_leaderboard پر می‌شد، پس XPی کاربرِ تازه هیچ‌وقت دیده نمی‌شد.
+        from django.core.cache import cache
+
+        from .leaderboard import compute_scores
+        scores = cache.get_or_set(
+            f'leaderboard:{period}', lambda: compute_scores(period), LEADERBOARD_CACHE_TTL,
+        )
+        entries = [
+            LeaderboardEntry(user_id=uid, period=period, xp_in_period=xp, rank=rank)
+            for rank, (uid, xp) in enumerate(scores, 1)
+        ]
 
         # نام کاربر از accounts.User خونده می‌شه (فقط برای نمایش، بدون FK واقعی).
         from accounts.models import User as AccountUser