fix heart refill and grant unlimited hearts to active subscribers

next_refill_at was set on UserHearts but never read or recalculated,
so a heart lost to zero never came back. UserHearts.apply_regen() now
catches up missed 24h intervals on read/deduct, and lose_heart() starts
the timer only when it isn't already running.

Any user with an active (non-expired) subscription now skips heart
deduction entirely, regardless of which plan they're on — good enough
for now until per-plan perks are needed.

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

progress/views.py

@@ -122,11 +122,18 @@ class UserHeartsView(APIView):
 
     @extend_schema(responses=UserHeartsResponseSerializer, tags=['Progress & Gamification (progress)'])
     def get(self, request):
+        from subscription.services import has_unlimited_hearts
+
         user = request.user
         hearts, _ = UserHearts.objects.get_or_create(user_id=user.id)
+        if hearts.apply_regen():
+            hearts.save(update_fields=['current_hearts', 'next_refill_at'])
+
+        unlimited = has_unlimited_hearts(user.id)
         data = {
-            'currentHearts': hearts.current_hearts,
+            'currentHearts': hearts.max_hearts if unlimited else hearts.current_hearts,
             'maxHearts': hearts.max_hearts,
-            'nextRefillAt': hearts.next_refill_at,
+            'nextRefillAt': None if unlimited else hearts.next_refill_at,
+            'isUnlimited': unlimited,
         }
         return Response(UserHeartsResponseSerializer(data).data)