Introduce activity grouping and summaries for consecutive reasoning/tool feed items (buildChatRenderItems, ActivityGroupCard, activityGroups) and add tests for activity grouping. Enhance message rendering to safely handle desktop-local file links (cowork-file:), rewrite file:// links, and confirm opening external links; add rehype-sanitize and a custom Streamdown link component. Improve bootstrapping to pick most-recent workspace/thread and auto-select on startup. Enable autoReconnect on control and thread sockets. Several UI/UX adjustments: prompt input sizing and layout, tool card styling, chat view feed rendering to use activity groups, and a redesigned PromptModal with suggested replies. Misc: small test and docs updates.
