complete admin CSS refactor: delete utilities.css, add layout primitives

- Delete utilities.css (701 lines / 24 KB of Tailwind utility clones)
- Add layout.css with admin-stack, admin-row, admin-cluster, admin-grid
  primitives and gap variants (sm, md, lg, xl)
- Add transitions.css import and layout.css import to admin.css entry point
- Replace all Tailwind utility classes across 26 admin templates with
  semantic admin-*/theme-*/page-specific CSS classes
- Replace all non-dynamic inline styles with semantic classes
- Add ~100 new semantic classes to components.css (analytics, dashboard,
  order detail, settings, theme editor, generic utilities)
- Fix stray text-error → admin-text-error in media.ex
- Add missing .truncate definition to admin CSS
- Only remaining inline styles are dynamic data values (progress bars,
  chart dimensions) and one JS.toggle target

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

lib/berrypod_web/live/admin/providers/index.html.heex

@@ -14,7 +14,7 @@
   </:actions>
 </.header>
 
-<div id="connections" phx-update="stream" class="admin-stack" style="margin-top: 1.5rem;">
+<div id="connections" phx-update="stream" class="admin-stack admin-card-spaced">
   <div id="connections-empty" class="hidden only:block">
     <div class="admin-empty-state">
       <.icon name="hero-cube" class="admin-empty-state-icon" />
@@ -41,9 +41,9 @@
     <div class="admin-card-body">
       <div class="admin-card-row">
         <div class="admin-card-content">
-          <div class="admin-row" style="--admin-row-gap: 0.5rem;">
+          <div class="admin-row">
             <.status_indicator status={connection.sync_status} enabled={connection.enabled} />
-            <h3 class="admin-card-title" style="margin-bottom: 0; font-size: 1.125rem;">
+            <h3 class="admin-card-title admin-section-heading admin-section-desc-flush">
               {provider_name(connection.provider_type)}
             </h3>
           </div>
@@ -64,7 +64,7 @@
             phx-click="delete"
             phx-value-id={connection.id}
             data-confirm={"Disconnect from #{provider_name(connection.provider_type)}? Your synced products will remain in your shop."}
-            class="admin-btn admin-btn-ghost admin-btn-sm text-error"
+            class="admin-btn admin-btn-ghost admin-btn-sm admin-text-error"
           >
             Disconnect
           </button>