Fixes two connected self-host setup failures in local worktree development.
Generated worktree environments now expose the backend HTTP origin through
MULTICA_PUBLIC_URL, and existing generated worktrees derive the missing value
at startup through both scripts/local-env.sh and the Makefile. Explicit
values, including an intentionally empty same-origin setting, are preserved.
setup and setup self-host now reconcile an existing same-profile daemon after
authentication so it loads the newly written server URL and token. An idle
daemon is restarted behind the existing restart preflight; when active tasks
exist, setup leaves the daemon running to avoid cancelling work and prints an
actionable profile-aware restart command instead.
Closes#5879
