reboot command beside poweroff, one polkit grant; forward yukart/gnss/+; mock uses current names

--allow-poweroff becomes --allow-power. deploy/50-yukart-gw-power.pkla adds logind's
reboot actions and the deploy removes the old poweroff-only file.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01DDwfd6Ki8UfG4hK6W5YpJz

docs/impl/plans/INITIAL.md

@@ -23,8 +23,8 @@ directly.
 0. **Boundary v0** — in place: WebSocket on `:7700`, hello, heartbeats both ways,
    `mark` forwarded to the recorder's control socket, mock state behind `--mock`.
    Protocol in contracts [`docs/BOUNDARY.md`](gitea:yukart/contracts).
-   **Bus input** — in place (2026-10-12): subscribes to `yukart/vehicle/+` and
-   `yukart/host/+`, keeps the newest envelope per signal, marks stale after 5 s
+   **Bus input** — in place (2026-10-12): subscribes to `yukart/vehicle/+`,
+   `yukart/host/+` and `yukart/gnss/+`, keeps the newest envelope per signal, marks stale after 5 s
    or when known only from a retained copy. Bus or mock, never both.
 1. Static file serving for the basemap — smallest useful thing, unblocks the map.
 2. Nav HTTP proxy to [svc-nav](gitea:yukart/svc-nav).