fix(downloads): Facebook files get their upload date, non-Latin names their letters

Since 2026-10-28 the signed-in Facebook read gives no upload date, so
every Facebook file since was named 0000-00-00 in Season_0 (31 on prod,
none before). The signed-out read that already titles these downloads
carries the date, so it now lends that too when the signed-in read has
none (backfill.public_title_info is now public_page_info).

On-disk names dropped every letter outside the Latin script, so a Hebrew,
Cyrillic, Greek or CJK uploader went to one shared "untitled" folder
(prod asset 503). anyascii now writes them in Latin letters
(Сергей Иванов -> Sergei_Ivanov); Latin and accented names are unchanged.

backend/app/downloads/backfill.py

@@ -8,7 +8,7 @@ Facebook sources (a direct media URL like a reddit HLS manifest carries no chann
 URL may have expired — those just get a locally-generated poster instead). A Facebook download
 titled with the source's placeholder ("Facebook", "Video") is retitled from a signed-out read of its
 page, and so is each download name that only repeated the placeholder. That page read
-(`public_title_info`) also titles every new download, from the worker.
+(`public_page_info`) also titles and dates every new download, from the worker.
 
 Run once per environment:
     docker exec siftlode-worker-1 python -c "from app.downloads import backfill; print(backfill.run())"
@@ -71,16 +71,23 @@ def _extract_meta_scoped(url: str, adapter: adapters.SourceAdapter, asset_id: in
     return None
 
 
-def public_title_info(info: dict, url: str, adapter: adapters.SourceAdapter, asset_id: int) -> dict:
-    """`info` to title a download from: itself, unless its title is a source's placeholder with
-    nothing behind it (a signed-in Facebook read: "Facebook", no description). Then one signed-out,
-    metadata-only read of the page lends its text — the description, else its title — as the
-    description the adapter takes a placeholder's title from. Nothing better there: `info` as it was."""
+def public_page_info(info: dict, url: str, adapter: adapters.SourceAdapter, asset_id: int) -> dict:
+    """`info` to title and date a download from: itself, unless its title is a source's placeholder
+    with nothing behind it (a signed-in Facebook read: "Facebook", no description). Then one
+    signed-out, metadata-only read of the page lends its text — the description, else its title — as
+    the description the adapter takes a placeholder's title from, and its upload date when `info` has
+    none (measured on prod: the signed-in read lost both on 2026-10-28, so every Facebook file since
+    was named 0000-00-00 in Season_0). Nothing better there: `info` as it was."""
     if not adapter.is_placeholder_title(adapter.title(info)):
         return info
-    public = extract_meta(url, adapter, asset_id)
-    text = public and (public.get("description") or public.get("title"))
-    return {**info, "description": text} if text else info
+    public = extract_meta(url, adapter, asset_id) or {}
+    lent: dict = {}
+    text = public.get("description") or public.get("title")
+    if text:
+        lent["description"] = text
+    if not info.get("upload_date") and public.get("upload_date"):
+        lent["upload_date"] = public["upload_date"]
+    return {**info, **lent} if lent else info
 
 
 def _retitle(db: Session, a: MediaAsset, adapter: adapters.SourceAdapter, url: str) -> bool:
@@ -88,7 +95,7 @@ def _retitle(db: Session, a: MediaAsset, adapter: adapters.SourceAdapter, url: s
     names that only repeated it. A name its owner gave (anything else) stays."""
     if not adapter.is_placeholder_title(a.title):
         return False
-    info = public_title_info({"title": a.title, "description": None}, url, adapter, a.id)
+    info = public_page_info({"title": a.title, "description": None}, url, adapter, a.id)
     named = normalize_title(adapter.title(info))
     if not named or adapter.is_placeholder_title(named):
         return False