fix(header): show sync activity only while a job is actually running

The header's sync indicator spun "fetching history" whenever any channel
still lacked full history — i.e. perpetually, even when the scheduler was
idle between its periodic runs. It now spins only while a channel-sync job
(backfill or RSS poll) is actually running; otherwise pending deep-history
work shows as the calm, static "N without full history" link, and recent
work queued for the next run shows a static "N queued". This makes the
header coherent with the Scheduler dashboard's live state.

Backend exposes running_job_ids() from the scheduler activity and a derived
sync_active flag on /api/sync/my-status.

frontend/src/components/SyncStatus.tsx

@@ -1,6 +1,6 @@
 import { useMutation, useQuery, useQueryClient } from "@tanstack/react-query";
 import { useTranslation } from "react-i18next";
-import { Database, History, Loader2, Pause, Play } from "lucide-react";
+import { Clock, Database, History, Loader2, Pause, Play } from "lucide-react";
 import { api } from "../lib/api";
 import { formatViews } from "../lib/format";
 import Tooltip from "./Tooltip";
@@ -38,6 +38,10 @@ export default function SyncStatus({
 
   const syncing = data.channels_recent_pending;
   const notFull = data.channels_deep_pending; // your channels without full history yet
+  // Spin only while a sync job is actually running; otherwise pending work shows as a calm,
+  // static state (or, for deep history, just the "N without full history" link below).
+  const active = data.sync_active;
+  const showMain = data.paused || active || syncing > 0 || notFull === 0;
 
   return (
     <div className="hidden lg:flex items-center gap-2 text-xs text-muted">
@@ -54,23 +58,31 @@ export default function SyncStatus({
           </span>
         </span>
       </Tooltip>
-      <span className="opacity-40">·</span>
-      {data.paused ? (
-        <span className="text-accent font-medium">{t("header.sync.paused")}</span>
-      ) : syncing > 0 ? (
-        <span className="flex items-center gap-1">
-          <Loader2 className="w-3.5 h-3.5 animate-spin" />
-          {t("header.sync.syncing", { count: syncing })}
-        </span>
-      ) : notFull > 0 ? (
-        // Recent uploads are in, but the scheduler is still backfilling full history —
-        // so "all synced" would be misleading. Reflect the deep work as active.
-        <span className="flex items-center gap-1">
-          <Loader2 className="w-3.5 h-3.5 animate-spin" />
-          {t("header.sync.backfillingHistory")}
-        </span>
-      ) : (
-        <span>{t("header.sync.allSynced")}</span>
+      {showMain && (
+        <>
+          <span className="opacity-40">·</span>
+          {data.paused ? (
+            <span className="text-accent font-medium">{t("header.sync.paused")}</span>
+          ) : active ? (
+            // A sync job is running right now — spin and name what it's doing.
+            <span className="flex items-center gap-1">
+              <Loader2 className="w-3.5 h-3.5 animate-spin" />
+              {syncing > 0
+                ? t("header.sync.syncing", { count: syncing })
+                : notFull > 0
+                  ? t("header.sync.backfillingHistory")
+                  : t("header.sync.working")}
+            </span>
+          ) : syncing > 0 ? (
+            // Recent uploads queued for the next run, but nothing running now — static.
+            <span className="flex items-center gap-1">
+              <Clock className="w-3.5 h-3.5" />
+              {t("header.sync.recentQueued", { count: syncing })}
+            </span>
+          ) : (
+            <span>{t("header.sync.allSynced")}</span>
+          )}
+        </>
       )}
       {notFull > 0 && (
         <>

frontend/src/i18n/locales/de/header.json

@@ -31,6 +31,8 @@
     "paused": "pausiert",
     "syncing": "{{count}} werden synchronisiert",
     "backfillingHistory": "Verlauf wird geladen",
+    "working": "Synchronisierung…",
+    "recentQueued": "{{count}} in Warteschlange",
     "allSynced": "alles synchronisiert",
     "withoutFullHistory": "{{count}} ohne vollständigen Verlauf",
     "fullHistoryTooltip": "Einige deiner Kanäle haben nur ihre neuesten Uploads. Klicke, um die Kanalverwaltung (auf diese gefiltert) zu öffnen und ihren vollständigen Katalog anzufordern.",

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

@@ -31,6 +31,8 @@
     "paused": "paused",
     "syncing": "{{count}} syncing",
     "backfillingHistory": "fetching history",
+    "working": "syncing…",
+    "recentQueued": "{{count}} queued",
     "allSynced": "all synced",
     "withoutFullHistory": "{{count}} without full history",
     "fullHistoryTooltip": "Some of your channels only have their recent uploads. Click to open the channel manager (filtered to these) and request their full back-catalog.",

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

@@ -31,6 +31,8 @@
     "paused": "szüneteltetve",
     "syncing": "{{count}} szinkronizálás alatt",
     "backfillingHistory": "előzmény letöltése",
+    "working": "szinkronizálás…",
+    "recentQueued": "{{count}} sorban",
     "allSynced": "minden szinkronban",
     "withoutFullHistory": "{{count}} teljes előzmény nélkül",
     "fullHistoryTooltip": "Néhány csatornádnak csak a legutóbbi feltöltései vannak meg. Kattints a csatornakezelő megnyitásához (ezekre szűrve), és kérd le a teljes archívumukat.",

frontend/src/lib/api.ts

@@ -316,6 +316,7 @@ export interface MyStatus {
   quota_used_today: number;
   quota_remaining_today: number;
   paused: boolean;
+  sync_active: boolean; // a channel-sync job (backfill/rss) is running right now
 }
 
 export interface MyUsage {