Documents list later UX pass

[HMarzban]

Parent

#173

What to build

A later UI/UX pass on Settings → Documents. Favorites already shipped (083acad3f). Do not redo Favorite persist, the ⋮ action, or pin-first ordering.

Walk the live list and grid after Favorites. Fix only what still fails:

• Grid preview is a generic file icon on a large base-200 band. Low signal. Thumbnails stay out of scope unless the maintainer reopens that.
• Grid footer (avatars + date + ⋮) crowds on narrow cards.
• List hides the date on small screens; grid always shows it.
• Grid has no arrow-key roving; list does.
• Create document is empty-state only.
• Lock/eye at /50 ink — check contrast on light and dark.

Acceptance criteria

• Empty grid preview is quieter or more useful without screenshot thumbnails.
• Grid footer does not crowd on a two-column narrow card.
• Date visibility is consistent between list and grid, or the difference is intentional and documented.
• Grid has keyboard roving that matches the list, or the gap is documented as accepted.
• Create document stays empty-state only, or the maintainer asks for a toolbar control.
• Lock/eye contrast meets the design-system bar on light and dark.

Out of scope

• Favorite persist, ⋮ Favorite/Unfavorite, pin-first ordering, or a toolbar star.
• Chat Bookmark or message Pin.
• Time-bucket headers, screenshot thumbnails, Last opened sort.

Blocked by

None. Can start after #173's first slice is on origin (push of 083acad3f).