fix(phase1): backfill pagination, fix card stacking, unify archive render

- Backfill aksrt_render_pagination() into inc/helpers/aksrt-template-tags.php
  (numbered + load_more/infinite branches, \AKSRT\Settings\Settings facade)
- post-card.css: drop display:block !important from base .posts-item so
  .posts-item.card inline-block 3-col grid wins; scope <posts> block forcing
- archive-resources.php: replace hand-written .posts-row.ajaxpager +
  get_template_part loop with aksrt_render_post_list() + aksrt_render_pagination()

Refs .specs/plans/zibll-widgets-1to1.md Phase 1 (US2/US3/US5)

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

assets/css/frontend/post-card.css

@@ -28,8 +28,6 @@
 posts.posts-item,
 article.posts-item,
 .posts-item {
-    /* Custom element <posts> is inline by default — force block layout. */
-    display: block !important;
     opacity: 1 !important;
     visibility: visible !important;
     padding: 20px;
@@ -45,6 +43,12 @@ article.posts-item,
     opacity: 1;
 }
 
+/* Custom element <posts> is inline by default — force block layout here only,
+   scoped so it never overrides .posts-item.card inline-block grid (Phase 1 fix). */
+posts.posts-item {
+    display: block;
+}
+
 .posts-item.list {
     display: block;
     width: 100%;