Toggle tasks and edit view settings via htmx

Task checkboxes post themselves (hx-post="?toggle=N") and flip back when
the save fails, replacing tasks.js. View settings are a server-rendered
form dialog with real radios and a select, replacing view-settings.js;
with that, postReplace has no callers left.

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

main.go

@@ -302,7 +302,7 @@ func (h *handler) serveDir(w http.ResponseWriter, r *http.Request, urlPath, fsPa
 		return
 	}
 	if r.URL.Query().Has("dialog") {
-		h.serveDialog(w, r, urlPath)
+		h.serveDialog(w, r, urlPath, fsPath)
 		return
 	}
 
@@ -406,8 +406,6 @@ func (h *handler) serveDir(w http.ResponseWriter, r *http.Request, urlPath, fsPa
 		Content:        rendered,
 		Entries:        entries,
 		View:           view,
-		Sort:           sortKey,
-		Order:          order,
 		SpecialContent: specialContent,
 		SidebarWidget:  sidebarWidget,
 		SuppressTOC:    suppressTOC,