decruft: re-add Bootstrap alert + pagination partials (used live)

The subset dropped two partials that are actually used: .alert (contact-form
success/error in inc/tweaks.php) and .pagination (paginate_links helper in
inc/template.php). Re-added both (small). Mark Bootstrap subset done in the checklist.

_claude/notes/dependencies.md

@@ -34,7 +34,7 @@ whole messenger/online-status feature, page-chat + `chat.*`, `terminal.js`, `mod
 
 | Chunk | Size | Drop when |
 |---|---|---|
-| Bootstrap 5 **full** (via `styles.scss`) | ~bulk | subset to used components (container/grid/carousel/offcanvas/nav) |
+| ~~Bootstrap 5 full~~ → **subset** | −49 KB | **✅ DONE 2026-06-21** — only used partials imported (grid/offcanvas/carousel/nav/forms/buttons/tables/list-group/card/pagination/alert + utilities API); dropped modal/dropdown/tooltip/popover/accordion/toasts/etc. Full removal still the end-goal. |
 | animate.css | 93 KB | WOW removed (→ IntersectionObserver/CSS) — drops together |
 | fullcalendar CSS | 40 KB | About-only → conditional-load, or replace calendar |
 | `style.css` custom | 58 KB | per-page: `.entry-content`/`.posts-front`/`.archive-page`/carousel rules die as each page blockifies |

css/styles.scss

@@ -79,6 +79,8 @@ $offcanvas-vertical-height: 100px !important;
 @import '../node_modules/bootstrap/scss/nav';
 @import '../node_modules/bootstrap/scss/navbar';
 @import '../node_modules/bootstrap/scss/card';
+@import '../node_modules/bootstrap/scss/pagination';
+@import '../node_modules/bootstrap/scss/alert';
 @import '../node_modules/bootstrap/scss/list-group';
 @import '../node_modules/bootstrap/scss/close';
 @import '../node_modules/bootstrap/scss/carousel';