fix(files): a steady list header, every user on the Storage tab, the name gets the row's room

- The Files list starts at the scroller's top: the padding above it let the sticky header ride up
  12px on the first scroll, then stop.
- Users -> Storage lists every user with their quota, not only those already holding a file — a
  quota is set before anyone downloads.
- On a wide Files list only the "…" holds a place; Copy link, Share and Save come up over the date
  while the row is hovered or holds the keyboard (a card keeps them in its line). Keeps is narrower.

backend/app/routes/downloads.py

@@ -856,19 +856,18 @@ def admin_storage(admin: User = Depends(admin_user), db: Session = Depends(get_d
         select(func.count(), func.coalesce(func.sum(MediaAsset.size_bytes), 0)).where(quota.ON_DISK)
     ).one()
     total_assets = db.execute(select(func.count()).select_from(MediaAsset)).scalar()
-    per_user = db.execute(
-        select(DownloadJob.user_id, func.count(func.distinct(DownloadJob.asset_id)))
-        .where(DownloadJob.asset_id.is_not(None))
-        .group_by(DownloadJob.user_id)
-    ).all()
-    uids = [uid for uid, _ in per_user]
-    emails = {u.id: u.email for u in db.execute(select(User).where(User.id.in_(uids))).scalars()}
+    # EVERY user, not only those holding a file: a quota is set before anyone downloads.
+    emails: dict[int, str] = {
+        uid: email
+        for uid, email in db.execute(select(User.id, User.email).order_by(User.email)).tuples()
+    }
+    uids = list(emails)
     # What each one's Files lists: their finished files.
     files: dict[int, int] = {
         uid: n
         for uid, n in db.execute(
             select(DownloadJob.user_id, func.count())
-            .where(DownloadJob.user_id.in_(uids), DownloadJob.status == JobStatus.DONE)
+            .where(DownloadJob.status == JobStatus.DONE)
             .group_by(DownloadJob.user_id)
         ).tuples()
     }
@@ -877,7 +876,7 @@ def admin_storage(admin: User = Depends(admin_user), db: Session = Depends(get_d
         lim = quota.resolve(db, uid)
         return {
             "user_id": uid,
-            "email": emails.get(uid),
+            "email": emails[uid],
             "footprint_bytes": quota.footprint(db, uid),
             "files": files.get(uid, 0),
             "max_bytes": lim.max_bytes,