feat(downloads): granular post-processing phase labels

ffmpeg post-steps have no byte-progress, so instead of a silent 'Processing' the row now names
the current step (Merging / Extracting audio / Embedding thumbnail / Removing sponsors / Writing
metadata) with an indeterminate pulse. Byte-progress phases (video/audio) keep the % bar.
i18n en/hu/de.

backend/app/worker.py

@@ -246,15 +246,30 @@ def _make_progress_hook(job_id: int, asset_id: int):
     return hook
 
 
+def _pp_phase(pp: str) -> str:
+    """Map a yt-dlp postprocessor class name to a user-facing phase label. ffmpeg post-steps
+    aren't byte-progress operations (no %), so the UI shows the step name + an indeterminate
+    pulse — this makes the long merge/finalize legible instead of a silent 'Processing'."""
+    if "Merg" in pp:
+        return "merging"
+    if "ExtractAudio" in pp:
+        return "audio_extract"
+    if "Thumbnail" in pp:
+        return "thumbnail"
+    if "SponsorBlock" in pp or "ModifyChapters" in pp:
+        return "sponsorblock"
+    if "Metadata" in pp:
+        return "metadata"
+    return "processing"
+
+
 def _make_pp_hook(job_id: int):
-    """Postprocessor hook: surface the ffmpeg merge/convert/extract step so the bar shows a
-    'Merging/Processing' label instead of freezing at 100% after the streams finish."""
+    """Postprocessor hook: surface the current ffmpeg step so the bar shows a concrete label
+    (Merging / Embedding thumbnail / …) instead of freezing at 100% after the streams finish."""
 
     def hook(d: dict) -> None:
         if d.get("status") in ("started", "processing"):
-            pp = d.get("postprocessor") or ""
-            phase = "merging" if "Merg" in pp else "processing"
-            _set_job(job_id, phase=phase, speed_bps=None, eta_s=None)
+            _set_job(job_id, phase=_pp_phase(d.get("postprocessor") or ""), speed_bps=None, eta_s=None)
 
     return hook
 

frontend/src/components/DownloadCenter.tsx

@@ -36,7 +36,11 @@ const STATUS_CLS: Record<string, string> = {
   canceled: "text-muted",
 };
 
-const PHASE_KEYS = ["video", "audio", "merging", "processing"];
+// Byte-progress phases (show a % bar) vs ffmpeg post-steps (no %, indeterminate pulse).
+const DOWNLOAD_PHASES = ["video", "audio"];
+const PHASE_KEYS = [
+  "video", "audio", "merging", "audio_extract", "thumbnail", "sponsorblock", "metadata", "processing",
+];
 
 function StatusPill({ job }: { job: DownloadJob }) {
   const { t } = useTranslation();
@@ -116,8 +120,8 @@ function DownloadRow({
         </div>
         {running && (
           <div className="mt-1.5">
-            {job.phase === "merging" || job.phase === "processing" ? (
-              // No meaningful percentage during ffmpeg — show an indeterminate pulse.
+            {job.phase && !DOWNLOAD_PHASES.includes(job.phase) ? (
+              // ffmpeg post-steps aren't byte-progress — show an indeterminate pulse, no %.
               <div className="h-1.5 rounded-full bg-surface overflow-hidden">
                 <div className="h-full w-full bg-accent/60 animate-pulse" />
               </div>

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

@@ -41,6 +41,10 @@
     "video": "Video wird geladen",
     "audio": "Audio wird geladen",
     "merging": "Zusammenführen",
+    "audio_extract": "Audio wird extrahiert",
+    "thumbnail": "Vorschaubild einbetten",
+    "sponsorblock": "Sponsoren entfernen",
+    "metadata": "Metadaten schreiben",
     "processing": "Verarbeitung"
   },
   "actions": {

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

@@ -41,6 +41,10 @@
     "video": "Downloading video",
     "audio": "Downloading audio",
     "merging": "Merging",
+    "audio_extract": "Extracting audio",
+    "thumbnail": "Embedding thumbnail",
+    "sponsorblock": "Removing sponsors",
+    "metadata": "Writing metadata",
     "processing": "Processing"
   },
   "actions": {

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

@@ -41,6 +41,10 @@
     "video": "Videósáv letöltése",
     "audio": "Hangsáv letöltése",
     "merging": "Összefűzés",
+    "audio_extract": "Hang kinyerése",
+    "thumbnail": "Bélyegkép beágyazása",
+    "sponsorblock": "Szponzorok eltávolítása",
+    "metadata": "Metaadat írása",
     "processing": "Feldolgozás"
   },
   "actions": {