Add a Home button and fill icon gaps from NPS's newer symbol library

Two things pulled in from github.com/nationalparkservice/npmap5-plugins:

- A "Home" button (public/vendor/npmap-home-button/, NPS's own MapLibre
  control) pinned to the app's CENTER/ZOOM, sitting top-left on the map. Now
  that the URL hash permalink can open the map at any view, "current view"
  and "the default view" aren't the same thing anymore, so a quick way back
  to the default is worth having.

- npmap5-plugins bundles a newer, actively-maintained version of the same
  NPS symbol-library already used for POI_ICONS (confirmed by its
  maintainer to be the designated replacement for the older standalone
  repo: nationalparkservice/npmap5-plugins#4), with a much larger icon
  vocabulary and a simpler CC0 (public domain) license. All 25 icons
  already in use came back byte-identical from the new source, so this
  just repoints their attribution — but it also has icons the old repo
  didn't: `forest` (POI_ICONS) is now the official "wilderness" pictogram
  instead of hand-drawn, and three of the five previously icon-less
  Services/Activities tags (wifi, mobile data coverage, winter/snow
  camping) now have real icons too. Only bakery and vehicle wash still
  have no NPS equivalent.

docs/third-party-notices.adoc

@@ -23,6 +23,21 @@ BSD-3-Clause licensed.
 | https://github.com/protomaps/basemaps
 |===
 
+Also vendored under `public/vendor/`, but not BSD-3-Clause like the
+above — MIT-licensed per its own `package.json` (the monorepo's
+top-level `LICENSE.md` separately places the whole repo in the public
+domain as a work of the US government; either way, no attribution is
+required):
+
+[cols="1,1,2"]
+|===
+| Library | Version | Source
+
+| NPS Home Button (`home-button`)
+| 0.0.1-d
+| https://github.com/nationalparkservice/npmap5-plugins/tree/main/home-button
+|===
+
 Offline map text labels need font glyphs too (see
 `docs/architecture.adoc`), vendored under `public/vendor/fonts/` —
 SIL Open Font License, not BSD-3-Clause like the above: