feat: add conversation image previews and sharing

docs/data-flow.md

@@ -104,6 +104,8 @@ For each latest inbound text event, `MediaLibraryExchangeService` detects direct
 
 After the normal reply limiter waits, automation refreshes Matrix and rechecks that the same inbound request is still latest and that no image, boundary, seller signal, or other terminal state has appeared. It then uploads the private file to Matrix, sends an `m.image` event with a stable transaction ID, and only after confirmation sends the optional reciprocal text. If the image is confirmed but the text is not, the asset remains consumed and the conversation is handed to the operator rather than risking a duplicate.
 
+The conversation UI also supports an explicitly confirmed manual choice from this same eligible set. Its read endpoint reports request-matched options without exposing filesystem paths. The send endpoint refreshes the conversation inside the owning account's rate limiter, rechecks the latest inbound request and safety boundaries, reserves the selected asset in the same durable ledger, and uses the same Matrix image-plus-reciprocal delivery path. A successful manual share marks automation as user-overridden.
+
 Conversation performance is derived from the complete attributed inbound transcript. Engagement cannot become a prompt-learning example while automation is active, and a later decline, boundary, or upsell removes an earlier example before future prompts load it.
 
 ## Dashboard data and events