Boost page navigation with htmx

Links and GET forms to wiki pages swap the next page into .shell instead
of loading a new document: the server answers boosted requests and
history restores with a partial (title, page actions out-of-band, shell
content). The header stays, browsers without cross-document view
transitions (Firefox) no longer flash between pages, and the swap runs
as a same-document view transition. Files, the editor, internal
endpoints and POST forms still navigate normally.

Back/Forward refetch pages (no snapshots that could predate a move or
delete); the tree rail keeps its scroll position and the content column
returns to where it was. Mutation redirects swap their result in the
same way. Page scripts that assumed a fresh document now also run after
a swap (toc, contents, companion, scroll-sync, search actions) or
register once (fitness).

The e2e suite now also runs in Firefox.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

assets/fitness/fitness.js

@@ -2,6 +2,11 @@
 // reloads the page with that chart's query parameter updated. Plain GET
 // navigation — each view is distinct and bookmarkable, so no
 // postReplace/history handling is needed.
+// Boosted navigation re-runs this script on every visit; the listeners
+// are delegated to document, so register them once.
+if (!window.fitnessWired) {
+window.fitnessWired = true;
+
 document.addEventListener('change', function (e) {
     var url = new URL(window.location.href);
     var sel = e.target.closest('[data-fitness-range]');
@@ -72,3 +77,4 @@ document.addEventListener('pointermove', function (e) {
     tip.style.left = left + 'px';
     tip.style.top = top + 'px';
 });
+}