Sets up a git worktree for isolated feature work — creates the branch, configures the worktree, detects whether a dev server is already running, and handles project-specific setup. Trigger on: "create a worktree", "set up a new branch", "start work on issue #X", "work on this in isolation", "new worktree for", "start a feature branch", "create an isolated environment for", "set up worktree".
