fix(subscription): extend by absolute expiry timestamp, not floored days

- activate_subscription_days now adds timedelta to the real expires_at
  (max(now, current_expires)) instead of _days_until() floor value;
  prevents losing fractional time on each renewal (10d + 1d -> was 10d)
- return ceil day count for display consistency
- keep _days_until only for is_subscribed gate and support stats

VERSION

@@ -1 +1 @@
-0.1.0+81
+0.1.0+82

user_store.py

@@ -238,7 +238,11 @@ def ensure_subscription(user_id: int, db_path: str | None = None) -> None:
 
 
 def activate_subscription_days(user_id: int, days: int, db_path: str | None = None) -> int:
-    """Добавляет срок к текущей подписке и возвращает оставшиеся дни."""
+    """Добавляет срок к подписке и возвращает оставшиеся дни (ceil).
+
+    Сложение ведётся по абсолютному UTC-моменту истечения, без округления дней:
+    это исключает потерю дроби при каждой продлировке (было 10д + 1д -> 10д).
+    """
     if days <= 0:
         raise ValueError("Subscription days must be positive")
     with closing(connect(db_path)) as connection, connection:
@@ -246,12 +250,9 @@ def activate_subscription_days(user_id: int, days: int, db_path: str | None = No
         if not sub:
             raise RuntimeError("Subscription record not found")
         now = datetime.datetime.now(datetime.timezone.utc).replace(tzinfo=None)
-        current_days = _days_until(sub, now)
-        if current_days > 0:
-            current_expires = now + datetime.timedelta(days=current_days, seconds=1)
-            new_expires = current_expires + datetime.timedelta(days=days)
-        else:
-            new_expires = now + datetime.timedelta(days=days)
+        current_expires = _subscription_expires_at(sub)
+        base = max(now, current_expires) if current_expires is not None else now
+        new_expires = base + datetime.timedelta(days=days)
         connection.execute(
             """
             UPDATE subscriptions
@@ -260,7 +261,8 @@ def activate_subscription_days(user_id: int, days: int, db_path: str | None = No
             """,
             (new_expires.isoformat(), days, user_id),
         )
-        return max(0, (new_expires - now).days)
+        remaining_seconds = int((new_expires - now).total_seconds())
+        return -(-remaining_seconds // 86400) if remaining_seconds > 0 else 0
 
 
 def activate_subscription(user_id: int, months: int = 1, db_path: str | None = None) -> int: