fix(subscription): keep access until last second of the term

- is_subscribed used _days_until() (floor), blocking generation for the whole
  last day when <24h remained though subscription was still active; now checks
  absolute expiry timestamp (expires > now)
- covers all gated actions (post generation, ideas) via _check_subscription

VERSION

@@ -1 +1 @@
-0.1.0+83
+0.1.0+84

user_store.py

@@ -281,13 +281,19 @@ def deactivate_subscription(user_id: int, db_path: str | None = None) -> None:
 
 
 def is_subscribed(user_id: int, db_path: str | None = None) -> bool:
-    """Правда ли подписка активна (срок не истёк)."""
+    """Правда ли подписка активна (срок не истёк).
+
+    Проверяем по абсолютному UTC-моменту истечения, а не по целым оставшимся
+    дням: доступ действует до последней секунды срока, весь «последний день».
+    """
     sub = subscription_row(user_id, db_path)
-    if not sub:
+    if not sub or not sub["is_active"]:
         return False
-    if not sub["is_active"]:
+    expires = _subscription_expires_at(sub)
+    if expires is None:
         return False
-    return _days_until(sub) > 0
+    now = datetime.datetime.now(datetime.timezone.utc).replace(tzinfo=None)
+    return expires > now
 
 
 def add_post_samples(user_id: int, posts: list[str], db_path: str | None = None) -> list[str]: