feat(config): job intervals live in sysconfig, every setting says when it applies, the unread SponsorBlock default goes

An interval override was a row of its own table beside the one store every other admin knob uses; it
is now the `job_interval_<job>` sysconfig key (migration 0110 copies them over and drops the table).
The Scheduler page stays its one editor: the Configuration page and the setup wizard neither list nor
write those keys, since a write there would skip the reschedule.

Each ConfigSpec now states `applies` (required, no default). Every key is `live`, held by a scan that
finds no read at import time; a `restart` key is refused until the page can say so. A second scan
requires a reader for every key on the Configuration page — `sponsorblock_default` had none since it
was added, so it leaves the registry, the translations and the store.

backend/app/scheduler.py

@@ -11,11 +11,11 @@ from apscheduler.jobstores.base import ConflictingIdError
 from apscheduler.schedulers.background import BackgroundScheduler
 from sqlalchemy import select
 
-from app import audit, debugsession, jobruns, logs, logsink, progress, quota
+from app import audit, debugsession, jobruns, logs, logsink, progress, quota, sysconfig
 from app.config import settings
 from app.db import SessionLocal
 from app.downloads.gc import run_download_gc
-from app.models import Channel, SchedulerSetting
+from app.models import Channel
 from app.plex.sync import sync as run_plex_sync
 from app.plex.tmdb import run_enrich as run_tmdb_enrich
 from app.plex.tmdb import run_people_enrich
@@ -52,41 +52,19 @@ _manual_actor: contextvars.ContextVar[int | None] = contextvars.ContextVar(
     "manual_actor", default=None
 )
 
-# Each interval job's env/config default period (minutes). The admin can override any of
-# these at runtime (stored in scheduler_settings, applied live); see load_intervals.
+# Each interval job's env/config default period (minutes). The admin can override any of these at
+# runtime from the Scheduler page — a sysconfig key per job (`sysconfig.interval_key`), applied
+# live; see load_intervals.
 JOB_INTERVALS: dict[str, int] = {
-    "rss_poll": settings.rss_poll_minutes,
-    "enrich": settings.enrich_interval_minutes,
-    "backfill": settings.backfill_interval_minutes,
-    "autotag": settings.autotag_interval_minutes,
-    "shorts": settings.shorts_probe_interval_minutes,
-    "subscriptions": settings.subscriptions_resync_minutes,
-    "playlist_sync": settings.playlist_sync_minutes,
-    "maintenance": settings.maintenance_interval_minutes,
-    "explore_cleanup": settings.explore_cleanup_minutes,
-    "download_gc": settings.download_gc_minutes,
-    "plex_sync": settings.plex_sync_interval_min,
-    "plex_watch_sync": settings.plex_watch_sync_interval_min,
-    "plex_watch_reconcile": settings.plex_watch_reconcile_interval_min,
-    "tmdb_enrich": settings.tmdb_enrich_interval_min,
-    "people_enrich": settings.people_enrich_interval_min,
-    "audit_gc": settings.audit_gc_minutes,
-    "log_gc": settings.log_gc_minutes,
+    job: getattr(settings, attr) for job, attr in sysconfig.JOB_INTERVAL_DEFAULTS.items()
 }
-
-# Sane bounds for an admin-set interval (minutes).
-MIN_INTERVAL = 1
-MAX_INTERVAL = 1440  # one day
+MIN_INTERVAL = sysconfig.MIN_INTERVAL
+MAX_INTERVAL = sysconfig.MAX_INTERVAL
 
 
 def load_intervals(db) -> dict[str, int]:
-    """Effective per-job intervals: the env/config defaults overlaid with any admin overrides
-    saved in scheduler_settings."""
-    iv = dict(JOB_INTERVALS)
-    for row in db.execute(select(SchedulerSetting)).scalars():
-        if row.job_id in iv and row.interval_minutes:
-            iv[row.job_id] = row.interval_minutes
-    return iv
+    """Effective per-job intervals: each job's sysconfig override, else its env/config default."""
+    return {job: sysconfig.get_int(db, sysconfig.interval_key(job)) for job in JOB_INTERVALS}
 
 
 def apply_interval(db, job_id: str, minutes: int) -> int:
@@ -95,11 +73,7 @@ def apply_interval(db, job_id: str, minutes: int) -> int:
     if job_id not in JOB_INTERVALS:
         raise KeyError(job_id)
     minutes = max(MIN_INTERVAL, min(MAX_INTERVAL, int(minutes)))
-    row = db.get(SchedulerSetting, job_id)
-    if row is None:
-        db.add(SchedulerSetting(job_id=job_id, interval_minutes=minutes))
-    else:
-        row.interval_minutes = minutes
+    sysconfig.set_value(db, sysconfig.interval_key(job_id), minutes)
     db.commit()
     if _scheduler is not None and _scheduler.get_job(job_id) is not None:
         _scheduler.reschedule_job(job_id, trigger="interval", minutes=minutes)
@@ -434,7 +408,6 @@ def _audit_gc_job() -> None:
     # quota_retention_days and finished runs past job_run_retention_days (0 = keep forever, each).
     # Pure DB, no quota.
     def work(db):
-        from app import sysconfig
 
         reaped = audit.gc(db, sysconfig.get_int(db, "audit_retention_days"))
         quota_reaped = quota.gc(db, sysconfig.get_int(db, "quota_retention_days"))
@@ -449,7 +422,6 @@ def _log_gc_job() -> None:
     # Prune log_events rows older than log_retention_days — the limit the privacy policy states, so
     # this runs hourly rather than daily. Pure DB, no quota.
     def work(db):
-        from app import sysconfig
 
         days = sysconfig.get_int(db, "log_retention_days")
         reaped = logsink.gc(db, days)