split scheduling into scan + process windows, move controls to settings page

the old one-window scheduler gated only the job queue. now the scan loop and
the processing queue have independent windows — useful when the container
runs as an always-on service and we only want to hammer jellyfin + ffmpeg
at night.

config keys renamed from schedule_* to scan_schedule_* / process_schedule_*,
plus the existing job_sleep_seconds. scheduler.ts exposes parallel helpers
(isInScanWindow / isInProcessWindow, waitForScanWindow / waitForProcessWindow)
so each caller picks its window without cross-contamination.

scan.ts checks the scan window between items and emits paused/resumed sse.
execute.ts keeps its per-job pause + sleep-between-jobs but now on the
process window. /api/execute/scheduler moved to /api/settings/schedule.

frontend: ScheduleControls popup deleted from the pipeline header, replaced
with a plain Start queue button. settings page grows a Schedule section with
both windows and the job sleep input.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

server/api/scan.ts

@@ -5,6 +5,7 @@ import { log, error as logError, warn } from "../lib/log";
 import { getAllItems, getDevItems } from "../services/jellyfin";
 import { loadLibrary as loadRadarrLibrary, isUsable as radarrUsable } from "../services/radarr";
 import { upsertJellyfinItem } from "../services/rescan";
+import { isInScanWindow, msUntilScanWindow, nextScanWindowTime, waitForScanWindow } from "../services/scheduler";
 import { loadLibrary as loadSonarrLibrary, isUsable as sonarrUsable } from "../services/sonarr";
 
 const app = new Hono();
@@ -209,6 +210,19 @@ async function runScan(limit: number | null = null): Promise<void> {
 			continue;
 		}
 
+		// Honour the scan window between items so overnight-only setups don't hog
+		// Jellyfin during the day. Checked between items rather than mid-item so
+		// we don't leave a partial upsert sitting in flight.
+		if (!isInScanWindow()) {
+			emitSse("paused", {
+				until: nextScanWindowTime(),
+				seconds: Math.round(msUntilScanWindow() / 1000),
+			});
+			await waitForScanWindow();
+			if (signal.aborted) break;
+			emitSse("resumed", {});
+		}
+
 		processed++;
 		emitSse("progress", { scanned: processed, total, current_item: jellyfinItem.Name, errors, running: true });