feat(downloads): editor v2 — cut-list, join, aspect filmstrip + hover scrub

Rework VideoEditor around a segment cut-list: N draggable cut markers → segments, per-segment
keep/drop (eye toggle + dropped hatch), output = Separate files (one job per kept segment) or
Join into one (segments cut-list → one concatenated file). Per-segment numeric Start/End inputs.
Filmstrip fixed: aspect-correct tiles (no vertical squish) + YouTube-style hover-scrub thumbnail
from the sprite. EditSpec.segments type; editor v2 i18n (en/hu/de). Verified end-to-end in a real
browser (3-segment split, drop middle, join → 0:12 clip from a 0:19 source).

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

@@ -25,5 +25,21 @@
   "createN": "{{count}} Clips erstellen",
   "created_one": "{{count}} Clip zu deinen Downloads hinzugefügt",
   "created_other": "{{count}} Clips zu deinen Downloads hinzugefügt",
-  "failed": "Clip konnte nicht erstellt werden."
+  "failed": "Clip konnte nicht erstellt werden.",
+  "splitHere": "Hier teilen",
+  "output": {
+    "label": "Ausgabe",
+    "separate": "Einzelne Dateien",
+    "join": "Zu einer zusammenfügen"
+  },
+  "segment": "Segment {{n}}",
+  "keep": "Behalten",
+  "drop": "Verwerfen",
+  "kept": "Behalten",
+  "dropped": "Verworfen",
+  "keptSeg": "Behaltenes Segment",
+  "droppedSeg": "Verworfenes Segment",
+  "removeCut": "Schnitt entfernen",
+  "keptSummary": "{{n}} behalten · {{dur}}",
+  "createJoin": "Zusammengefügten Clip erstellen"
 }