release(v1.7.32-alpha): fix frontend tarball layout + mDNS shutdown hang

- HOTFIX: v1.7.31-alpha's frontend tarball was packaged with a
  `neode-ui/` top-level directory instead of the flat layout v1.7.30
  and earlier used. Nodes that applied v1.7.31 ended up with
  `/opt/archipelago/web-ui/neode-ui/index.html` instead of
  `/opt/archipelago/web-ui/index.html`, and nginx returned 403/500.
  v1.7.32's tarball is built with `tar -C web/dist/neode-ui .` so
  files land directly at web-ui root. Broken nodes auto-heal on this
  update (web-ui dir is replaced).
- transport/lan.rs: add Drop impl that calls ServiceDaemon::shutdown()
  on the mdns_sd daemon. Without this the OS thread it spawns, plus
  the blocking `receiver.recv()` task, keep the tokio runtime alive
  past SIGTERM — long enough for systemd's TimeoutStopSec to SIGKILL
  the service and mark it Failed. Was visible on every update:
  "shut down cleanly" logged, then 15s later systemd forcibly kills.
- main.rs: after logging "Archipelago shut down cleanly", call
  `std::process::exit(0)` explicitly. Belt-and-suspenders against
  any future non-daemon thread creeping in (reqwest resolver pool,
  etc.) and causing the same SIGKILL regression.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

core/archipelago/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "archipelago"
-version = "1.7.31-alpha"
+version = "1.7.32-alpha"
 edition = "2021"
 description = "Archipelago Bitcoin Node OS - Native backend"
 authors = ["Archipelago Team"]