Add links-mode embed thumbnails, item metadata, and media filters

CURRENT.md

@@ -40,6 +40,15 @@ 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] 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/
+    21:9/other), resolution preset (SD/HD/FHD/QHD/4K+/unknown, by shortest side), and a
+    posted-date range. UI: scrape popup with Server and Group-chat trees (server -> channels, each
+    with Links/Download), History popup (time, duration, pages/messages, media, bytes, files,
+    previews), live progress pulse, full-window view. Live run `...-20260916094120`: 11 previews
+    in links mode (embed thumbnails included), poster zzib, a 9:16 short stored as 0.563, and the
+    16:9 filter matched.
   - [x] C13 Embed thumbnails in download mode: embed rows cache their stored thumbnail URL;
     the full third-party media is never fetched. Live run `...-20260916091458` on the test
     channel: 6 files downloaded, 11 previews cached (YouTube, Reddit, Tenor, TikTok, X). Also