recap: Building a dedicated Book Talk thread screen (BOO-1022, PR #2855): list now navigates to a thread showing…

recap: Building a dedicated Book Talk thread screen (BOO-1022, PR #2855): list now navigates to a thread showing level-1 replies with nested ones collapsed. Latest change made the root post a rounded card and reply bubbles white. Next: you review it on device. (disable recaps in /config)