Add custom download destinations, confirmations, and the bot error feed

CURRENT.md

@@ -40,6 +40,13 @@ mobile draft at 390px.
   - [x] C11 preview caching: Discord-hosted image/GIF previews (WebP 320px, hash-addressed, 5 MiB
     cap, one attempt) run after every walk in both modes. Live run `...-20260916090722`:
     `previewed: 2`; thumbs served over `/api/media/<scrape>/<item>/thumb` (200).
+  - [x] C15 Scrape UX: custom download destination (absolute path per scrape; files there,
+    previews local, embed thumbnails copied to both, custom files not served), confirmation popup
+    before Links/Download, New scrape/History right-aligned with New scrape furthest right, modal
+    X and backdrop close, active-only progress strip, and a Bot error feed with a red unseen badge
+    that clears on open plus a Clear button. Live run `...-20260916095029`: 6 files and 7 embed
+    thumbnails in `/tmp/opencode/media-dest/<id>/`, 11 local previews, 0 local files, `localUrl`
+    null; error record and clear verified over the API.
   - [x] C14 Links-mode embed thumbnails, item metadata, filters, and the scrape popup. Metadata:
     poster (`author_id`/`author_name`), `posted_at`, `width`/`height`, `aspect_ratio`, with an
     `ffprobe` fallback after downloads. Filters: poster, aspect preset (vertical/square/4:3/16:9/