The maps page reset to the default US-wide view on every refresh because
initialViewState was hardcoded. Save the position and zoom to localStorage
on each move-end (key nomad:map-view, matching the existing scale-unit
pattern) and restore it at mount: saved view → default. The restore is
bounds-checked so a corrupt value falls through to the default.
Replaces #815, whose branch had drifted far out of scope (56 files of
stale-base/merged-commit noise plus unrelated map-feature WIP). This is
just the persist-view improvement, ported cleanly onto current dev. The
null-island and coordinate-search parts of #815 targeted URL-param code
that never landed on dev, so they don't apply here.
da60c6ce9c