Apply the NPS-inspired palette to the online map too

ONLINE_STYLE_PATCH mirrors OFFLINE_THEME's color choices onto
OpenFreeMap Liberty's OpenMapTiles layer ids (a separate hand-built
table -- the two schemas share no layer names). loadOnlineStyle
fetches Liberty's style.json once, patches it in place, and the
result replaces the plain URL everywhere ONLINE_STYLE is used --
MapLibre accepts a style object anywhere it accepts a style URL, so
applyStyle needed no change.

Runs before the map (and the rest of the page) is constructed, so
there's no flash of Liberty's own colors first -- but with a 3s
timeout and a catch-all fallback to the plain URL, since this app is
meant to keep working offline in the field and blocking startup on a
remote style server would undermine that.

Verified in a real browser: online map now visually matches the
offline theme (cream ground, brown/khaki land cover, green parks,
muted roads), no console errors, Online/Offline toggle still works.

docs/architecture.adoc

@@ -121,6 +121,31 @@ No PMTiles file ships with the repository — it is expected to be
 supplied locally (see `docs/development.adoc`) and stays gitignored
 because such extracts are typically large binary files.
 
+The Online map (OpenFreeMap Liberty) gets the same treatment via
+`ONLINE_STYLE_PATCH`, a separate hand-built table — Liberty is an
+OpenMapTiles-schema style, with its own layer ids (`landcover_wood`,
+`road_secondary_tertiary`, `boundary_2`, ...) that don't correspond to
+protomaps' theme roles, so the two palettes can't share one object,
+only the same underlying color choices. `loadOnlineStyle`
+(`public/js/map.js`) fetches Liberty's `style.json` once, patches it
+in place, and uses the resulting object everywhere `ONLINE_STYLE` used
+to be a plain URL string — MapLibre accepts a style object anywhere it
+accepts a style URL, so `applyStyle`'s `map.setStyle(... : ONLINE_STYLE)`
+needed no change. That fetch runs before the map (and the rest of the
+page) is constructed — a top-level `await` — so there's no flash of
+Liberty's own colors before the patch lands; a 3s timeout and a
+catch-all fall back to the plain URL (letting MapLibre fetch and
+render it unpatched) rather than block the whole page's startup on a
+remote style server, since this app is meant to keep working offline
+in the field, independent of whether the online map itself loads.
+Only the layers that dominate the map's overall color read are
+patched (land cover, water, parks, roads, boundaries, buildings) —
+same deliberately-partial scope as `OFFLINE_THEME`, not a full
+per-layer recolor. Road casings are the one addition with no
+protomaps-role equivalent to reuse, since offline roads don't get a
+separate outline color there; `#c9a66b` is reasoned to fit the family
+rather than sourced from anywhere real.
+
 == Map permalink
 
 The map's `hash: "map"` option (`public/js/map.js`) turns on MapLibre