Improve visual separation between memos / header/content contrast / clearer date-link affordance

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What problem would this solve & what would you like to happen?

The memo list currently has very little visual separation between individual memos, and the date link that opens a memo's detail view isn't clearly recognizable as a link. This affects both usability for new users and readability in general.

More visual separation between memos:

Memos are displayed with so little spacing between them that the whole list is perceived as one continuous block rather than a set of distinct entries. At first sight, it's hard to tell where one memo ends and the next begins. Plaese increase the vertical spacing between memos, or add another form of visual separation so each memo is clearly distinguishable at a glance.

Subtle contrast between memo header and content

The header of a memo currently blends in too much with the memo's body text. A slight visual distinction (a slightly different color or background tint for the header area) would make it easier to visually separate metadata from content without being distracting.

Make the date link more recognizable as a link

The date shown on each memo is actually the "unique link" that opens the full view of that memo, but this isn't visually obvious. New users, and especially anonymous visitors who only see public memos, have no clear indication that clicking the date does anything. This was also discussed in #6359. Please style the date more clearly as an interactive element (e.g. underline on hover, link color, icon, or similar) so it's evident that it's clickable.

More flexible date/time formatting options

While addressing point 3, it would also make sense to reconsider the date/time display itself: Please allow more flexible localization options for how the date/time is formatted and allow the admin to set a default date/time format for visitors who are not logged in (since they cannot set their own locale preference).

Additional context

No response