render 404, 405, and malformed-request errors as styled html pages instead of json

render a friendly html error instead of a json 422 when the compare or tax form is submitted empty

add optional cloudflare web analytics and suppress keep-alive pings from access logs

raise test coverage to 100% (152 tests)

add landing page; move relocation calculator to /relo and add tool nav

accept HEAD on / so platform health checks pass

add test suite covering model, fx, currencies, scraping and endpoints