A way down the tree from every page

An arrow fixed at the left edge, half-way up the screen, and the same
link in words at the foot of the page. It goes one level down: the
nearest page below the current path that the visitor may open, found by
taking the path apart a segment at a time, and the front door when none
of those is a page (/status/oppslag -> /, /review/abc -> /review). The
front door itself has none. Labelled with where it goes: 'Tilbake til
starten', or the target page's question in quotation marks.

Content stops needing a 'back' alternative on every page, and a visitor
who went up a branch whose context did not apply is never stranded.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01GT37Z1Xtfd9pUuQtMTg6Yt

CHANGELOG.md

@@ -4,6 +4,10 @@ One line per change, grouped by the release that shipped it. Newest
 first. A release is a Cargo.toml bump plus a `v<version>` tag; the
 content repos pin the tag they run (see the end of this file).
 
+## Unreleased
+
+- A way down the tree from every page: an arrow fixed at the left edge, half-way up, and the same link in words at the foot ("Tilbake til starten", "Back to “What came in?”"). It goes to the nearest page below the current one that the visitor may open, taking the path apart a segment at a time, and to the front door when none is; the front door has none. Content no longer needs a "back" alternative, and a visitor who went up a branch that turned out not to apply is never stranded.
+
 ## 0.5.2 (2026-09-28)
 
 - The rate limiter answered 500 to any request that arrived without `X-Forwarded-For`. It reads the caller from that header or `X-Real-IP` and falls back to the socket, and 0.5.0 served the app without connect info, so there was no socket to fall back to and no key to rate-limit by. Through Caddy every request carries the header and the site was fine; a health check on localhost got a 500, which is how the first deploy of 0.5.1 failed.