chore: rename remaining subfeed references to siftlode

Replace the leftover 'subfeed' name across logger names + log_config,
frontend localStorage keys, Postgres user/db/volume defaults in the
compose files, .env.example, config.py, backup/restore scripts and the
README. Pure rename; no behavioural change. localStorage keys move from
subfeed.* to siftlode.* (one-time UI-state reset is acceptable).

backend/app/sync/autotag.py

@@ -11,7 +11,7 @@ import re
 from sqlalchemy import and_, exists, func, select
 from sqlalchemy.orm import Session
 
-log = logging.getLogger("subfeed.autotag")
+log = logging.getLogger("siftlode.autotag")
 
 from app import progress, sysconfig
 from app.models import Channel, ChannelTag, Tag, Video

backend/app/sync/maintenance.py

@@ -34,7 +34,7 @@ from app.sync.runner import get_service_user
 from app.sync.videos import apply_video_details, parse_dt
 from app.youtube.client import YouTubeClient
 
-log = logging.getLogger("subfeed.maintenance")
+log = logging.getLogger("siftlode.maintenance")
 
 # Reasons recorded on Video.unavailable_reason. "removed" = absent from videos.list
 # (deleted or made private); "abandoned" = an upcoming premiere that never went live.

backend/app/sync/playlists.py

@@ -18,7 +18,7 @@ from app.models import Channel, OAuthToken, Playlist, PlaylistItem, User, Video
 from app.sync.videos import apply_video_details, parse_dt
 from app.youtube.client import YouTubeClient, YouTubeError
 
-log = logging.getLogger("subfeed.sync")
+log = logging.getLogger("siftlode.sync")
 
 # Cost of a single YouTube write op (playlists/playlistItems insert/update/delete).
 WRITE_UNIT_COST = 50

backend/app/sync/runner.py

@@ -12,7 +12,7 @@ from sqlalchemy.orm import Session
 
 from app import progress, quota, sysconfig
 
-log = logging.getLogger("subfeed.sync")
+log = logging.getLogger("siftlode.sync")
 from app.models import Channel, OAuthToken, Subscription, User
 from app.sync.subscriptions import import_subscriptions
 from app.sync.videos import (

backend/app/sync/subscriptions.py

@@ -8,7 +8,7 @@ from sqlalchemy.orm import Session
 from app.models import Channel, Subscription, User
 from app.youtube.client import YouTubeClient, best_thumbnail
 
-log = logging.getLogger("subfeed.sync")
+log = logging.getLogger("siftlode.sync")
 
 
 def _to_int(value) -> int | None: