feat: delay show rotation during live recording window

Decouple the like-window boundary (Wed 10pm ET) from when the system
rotates to a new show. NTR_SHOW_ROTATION_DELAY_HOURS=2 keeps the
previous week's show visible during the ~2 hour recording, then creates
the new show at midnight.

Made-with: Cursor

src/ntr_fetcher/poller.py

@@ -4,7 +4,7 @@ from datetime import datetime, timezone
 
 from ntr_fetcher.db import Database
 from ntr_fetcher.soundcloud import SoundCloudClient
-from ntr_fetcher.week import get_show_week
+from ntr_fetcher.week import get_current_show_week
 
 logger = logging.getLogger(__name__)
 
@@ -18,6 +18,7 @@ class Poller:
         show_day: int,
         show_hour: int,
         poll_interval: float,
+        rotation_delay_hours: float = 0,
     ):
         self._db = db
         self._sc = soundcloud
@@ -25,6 +26,7 @@ class Poller:
         self._show_day = show_day
         self._show_hour = show_hour
         self._poll_interval = poll_interval
+        self._rotation_delay_hours = rotation_delay_hours
         self._user_id: int | None = None
         self.last_fetch: datetime | None = None
         self.alive = True
@@ -37,7 +39,9 @@ class Poller:
     async def poll_once(self, full: bool = False) -> None:
         user_id = await self._get_user_id()
         now = datetime.now(timezone.utc)
-        week_start, week_end = get_show_week(now, self._show_day, self._show_hour)
+        week_start, week_end = get_current_show_week(
+            now, self._show_day, self._show_hour, self._rotation_delay_hours,
+        )
         show = self._db.get_or_create_show(week_start, week_end)
 
         if show.episode_number is None: