* Fix find_project_root hijacking git worktrees nested under a Serena project
find_project_root searched all ancestor levels for .serena/project.yml
before ever looking for .git. A git worktree whose own .git is a pointer
file, nested under a directory that is an explicit Serena project, was
resolved to the ancestor project instead of the worktree. With CLI agents
that launch via --project-from-cwd (Claude Code, Codex, Gemini), this
silently bound the server to the wrong working tree: reads returned stale
symbols and edits landed in the parent repo.
Walk up in a single pass so the nearest project boundary wins, whether it
is a .serena/project.yml or a .git (dir or worktree/submodule pointer
file). Same-level behavior is unchanged. Adds a regression test.
* Document worktree project-root fix in changelog and usage docs
* Remove obsolete/outdated content
* git-worktree:
- Remove incorrect recommendation to copy the entire .serena folder
in order to retain the cache (cache contains abs. paths)
- Recommend to add the .serena folder to version control instead
(which will not include the cache folder)
Relates to #805