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.

frontend/src/i18n/backendIds.contract.test.ts

@@ -10,7 +10,7 @@ import { vocabKey } from "../lib/vocab";
 // the registries straight from the backend sources:
 //   - `sysconfig.SPECS`      → `config.groups.<group>`, `config.fields.<key>.label` + `.hint`, and for a
 //     "choice" key `config.choices.<key>.<option>` — the options read from its Literal in config.py
-//   - `scheduler.JOB_INTERVALS` and `scheduler.AD_HOC_JOBS` → `scheduler.jobs.<id>` + `scheduler.jobDesc.<id>`
+//   - `sysconfig.JOB_INTERVAL_DEFAULTS` and `scheduler.AD_HOC_JOBS` → `scheduler.jobs.<id>` + `scheduler.jobDesc.<id>`
 //   - the `audit` action enum → `auditActions.<id>`; the `quota` action enum → `quotaActions.<id>`
 // and the other way round: a name left behind for an id the backend dropped is dead weight that reads
 // as a live setting to the next person (`plex_sync_interval_min` moved to the scheduler long ago).
@@ -57,12 +57,13 @@ const choiceIds = specs
   .filter((s) => s.type === "choice")
   .flatMap((s) => choicesOf(s.attr).map((c) => `config.choices.${s.key}.${c}`));
 const schedulerPy = backend("scheduler.py");
-// The interval jobs, and the ad-hoc ones (`AD_HOC_JOBS`, a tuple of constants named beside it).
+// The interval jobs (sysconfig's `JOB_INTERVAL_DEFAULTS`: job → its default's setting), and the
+// ad-hoc ones (`AD_HOC_JOBS` in scheduler.py, a tuple of constants named beside it).
 const jobs = [
   ...[
-    ...(schedulerPy.split("JOB_INTERVALS")[1] ?? "")
+    ...(backend("sysconfig.py").split("JOB_INTERVAL_DEFAULTS: dict[str, str] = {")[1] ?? "")
       .split("}")[0]!
-      .matchAll(/"(\w+)": settings\./g),
+      .matchAll(/"(\w+)": "\w+",/g),
   ].map((m) => m[1]!),
   ...[...(/^AD_HOC_JOBS = \(([^)]*)\)/m.exec(schedulerPy)?.[1] ?? "").matchAll(/\b[A-Z_]+\b/g)].map(
     (m) => new RegExp(`^${m[0]} = "(\\w+)"$`, "m").exec(schedulerPy)?.[1] ?? m[0],

frontend/src/i18n/locales/en/config.json

@@ -162,10 +162,6 @@
       "label": "Worker concurrency",
       "hint": "How many downloads the worker processes in parallel."
     },
-    "sponsorblock_default": {
-      "label": "SponsorBlock by default",
-      "hint": "Enable SponsorBlock (skip sponsor segments) for newly created custom download profiles."
-    },
     "audit_retention_days": {
       "label": "Retention (days)",
       "hint": "How long admin audit-log entries are kept before the audit-log cleanup job prunes them. 0 = keep forever. Default 180."

frontend/src/i18n/locales/hu/config.json

@@ -162,10 +162,6 @@
       "label": "Párhuzamos letöltések",
       "hint": "Hány letöltést dolgoz fel egyszerre a letöltő folyamat."
     },
-    "sponsorblock_default": {
-      "label": "SponsorBlock alapból",
-      "hint": "SponsorBlock (szponzorszakaszok átugrása) bekapcsolása az újonnan létrehozott egyéni letöltési profilokhoz."
-    },
     "audit_retention_days": {
       "label": "Megőrzés (nap)",
       "hint": "Meddig maradnak meg az admin-naplóbejegyzések, mielőtt az eseménynapló-takarító feladat törli őket. 0 = örökre. Alapérték 180."