refactor: centralize page filtering logic, and allow sort by lastmod (#1250)

* refactor: migrate page visibility control from `Params.hidden` to the new `build.list` parameter.

* refactor: centralize page filtering logic into a new `helper/pages.html` partial

* feat: introduce `SortBy` parameter to enable sorting pages by last modified date

* refactor: extract page sorting logic into a new `pages-sort.html` partial

config/_default/params.toml

@@ -2,6 +2,11 @@ mainSections       = ["post"]
 featuredImageField = "image"
 rssFullContent     = true
 
+# Accepted values: "default", "lastmod"
+# default = see https://gohugo.io/quick-reference/glossary/#default-sort-order
+# lastmod = sort by last modified date, in descending order
+SortBy              = "default"
+
 [footer]
     since      = 2026
     customText = ""