Session tree nests by working directory only; the daemon chips in the header become a session tally, and the spawn form loses its host picker. API calls move from /api/daemons/:id/* to /api/dirs, /api/recent-dirs, /api/gitroot, and /api/info.
Adds api.listDir + a reusable dirAutocomplete widget (live dropdown, Tab/Enter completion, /-drill-in, per-(daemon,dir) cache) wired onto the cwd and worktree base-repo fields, with matching dropdown styling.