feat(hugo): replace deprecated APIs for Hugo v0.156+ compatibility

Migrate site.Data → hugo.Data (42 occurrences), site.IsMultiLingual →
hugo.IsMultilingual, and site.AllPages → hugo.Sites nested range.
Simplify Netlify redirects template to use pre-processed aliases
instead of relLangURL per gohugoio/hugo#14408.

modules/blox/layouts/_partials/components/headers/navbar-simple.html

@@ -104,7 +104,7 @@
         <li class="lg:px-2">
           <select onchange="document.documentElement.setAttribute('data-theme-pack', this.value); localStorage.setItem('hb-theme-pack', this.value);" class="bg-transparent text-[var(--hb-color-header-fg)] border-none focus:ring-0 cursor-pointer text-sm font-medium">
             <option value="">Theme</option>
-            {{ range $name, $data := site.Data.themes }}
+            {{ range $name, $data := hugo.Data.themes }}
               <option value="{{ $name }}">{{ $name | humanize }}</option>
             {{ end }}
           </select>

modules/blox/layouts/_partials/components/headers/navbar.html

@@ -181,7 +181,7 @@
       <div class="px-3">
         <select onchange="document.documentElement.setAttribute('data-theme-pack', this.value); localStorage.setItem('hb-theme-pack', this.value);" class="bg-transparent text-[var(--hb-color-header-fg)] border-none focus:ring-0 cursor-pointer text-sm font-medium">
           <option value="">Theme</option>
-          {{ range $name, $data := site.Data.themes }}
+          {{ range $name, $data := hugo.Data.themes }}
             <option value="{{ $name }}">{{ $name | humanize }}</option>
           {{ end }}
         </select>