feat(i18n): every server A→Z list in the reader's alphabet (E30 S3)

The Postgres image is Alpine, whose en_US.utf8 is byte order: "Életrajzi" and
"Ötödik" sorted after "Zorró" in the feed, the channel lists, the Plex grid,
its genres and collections. `app/collation.py` names the ICU collation of the
reader's language (hu-x-icu puts "Ö" after "O" and "Cs" after "Cu"), wraps
every text ORDER BY with it - the feed's keyset cursor compares with the same
expression, so paging walks the order it sorted in - and orders the lists built
in Python (genre and studio facets, collection members, the discovery re-sort)
through the same collation. Plex title tiebreaks use the shown (HU) title.

backend/app/routes/downloads.py

@@ -21,6 +21,8 @@ from pydantic import BaseModel
 from sqlalchemy import func, select
 from sqlalchemy.orm import Session
 
+from app.mailtext import lang_for_user
+from app.collation import collated
 from app import audit, sysconfig
 from app.auth import admin_user, require_human
 from app.config import settings
@@ -988,7 +990,7 @@ def share_recipients(
         db.execute(
             select(User)
             .where(User.id != user.id, *messageable_clauses())
-            .order_by(func.lower(User.email))
+            .order_by(collated(User.email, lang_for_user(user)))
         )
         .scalars()
         .all()