v0.20.0

• keep HOME in the jj test helper so repo config reaches the backend on macOS
• pin the jj test remote's HEAD to main so CI's master default can't break pull tests
• trim AGENTS.md to an index and move design notes into docs/architecture
• run jj's own verbs: push, pull, commit selected files and a change menu
• read jj repos the jj way: no .git needed, change ids, bookmarks and revsets
• tighten the MCP tool descriptions and move field rules onto their fields
• untangle the diff screen modules and share golden-angle colours
• split ui/diff.rs into a module per part of the diff screen
• split the diff screen's state into sidebar, folds and topic test files
• let the agent edit or delete any local comment, the human's included
• draw the log as a branch graph and add l b for every branch
• copy or open the forge link to the file view's lines with Y and gx
• wrap comment cards to the diff pane's width beside the comments pane
• let the agent take the human to a comment, walkthrough or line in any review
• apply language rules to the symbol lens and walkthrough anchors

Full changelog: v0.19.1...v0.20.0