Chat friendly UI to display Direct Message

[ArtificialOwl]

A new interface to shows Direct Message should be implemented. The DM timeline should not be displayed as a timeline but like a modern chat app, with a list of recipients that open the full discussion between the user and the recipient.

[violoncelloCH]

@jancborchardt's notes from the design review:

• Needs a 2nd column to filter messages by person – like Twitter, or our Mail or Contacts app
• Avatar of the person, name of the person as main line, last message as subline
• In the content view sorted by newest on the bottom and input field on the bottom
• → Basically let’s do it like twitter

[ArtificialOwl]

adding the tag backend as there is a lot of work on the db side to efficiently retrieve data based on recipients

[SchBenedikt]

Social already has a conversations API and persisted read/dismissed state, but PR #2291 confirms that it does not add the requested dedicated chat-style conversation UI. This remains open; the existing API is not presented as a UI fix. Audit notes: #2291

[SchBenedikt]

Implemented in PR #2291: the direct timeline now opens as a conversation list with a responsive thread view, loads the complete stored context, supports direct replies, and marks conversations read on open. The selected conversation is shareable through the route query. The PR includes UI and localization regressions plus architecture documentation; this issue will close when the PR merges.