pres_mgmt: redesign Session View, clean Presentation list, fix transitions

- session_view.svelte: replace flat <ul> with hero card layout
  - Name as <h1>, date/time chip (primary teal), room chip (tertiary indigo)
  - QR only rendered when URL is string (not true loading placeholder)
  - Skeleton pulse placeholders while LiveQuery resolves
  - Description in surface card with uppercase label
  - Accessible: aria labels, focus rings, aria-live on no-results section
- ae_comp__event_session_obj_li.svelte:
  - variant-soft-warning (Skeleton v3) -> preset-tonal-warning (v4)
  - Add transition-colors duration-200 to <tr> rows and session <a> links
- ae_comp__event_presentation_obj_li.svelte:
  - Remove debug breakpoint border colors (red/yellow/gray)
  - overflow-x-scroll -> overflow-x-auto
  - Remove heavy preset-filled-surface-400-600 from <ul> container
  - <li> cards: surface tokens, rounded-xl, shadow-sm, transition
  - <h4> title bar: bg-surface-100-900 with flex wrap layout
  - Code badge: hardcoded yellow -> preset-tonal-warning
  - Description <pre>: hardcoded bg-gray-100 -> bg-surface-100-900
- pres_mgmt/+page.svelte: 'no results' section
  - bg-yellow-100 + text-yellow-500 -> preset-tonal-warning
  - Search icon, aria-live, cleaner list in surface card
- [session_id]/+page.svelte: rounded-container-token (v3) -> rounded-xl

src/routes/events/ae_comp__event_presentation_obj_li.svelte

@@ -53,16 +53,7 @@
 </script>
 
 <section
-    class="
-    ae_comp event_presentation_obj_li
-    border-dashed border-y-transparent border-r-transparent
-    sm:border-l-red-400 md:border-l-yellow-400 lg:border-l-gray-100
-    sm:dark:border-l-red-600 md:dark:border-l-yellow-600 lg:dark:border-l-gray-700
-    px-0.5 py-2 space-y-2
-    min-w-full
-    w-full
-    container overflow-x-scroll {container_class_li}
-    "
+    class="ae_comp event_presentation_obj_li px-0.5 py-2 space-y-2 min-w-full w-full container overflow-x-auto {container_class_li}"
 >
     <div class="float-right flex flex-row items-center">
         {#if $ae_loc.trusted_access && $ae_loc.edit_mode}
@@ -126,9 +117,9 @@
     </h3>
 
     <!-- Show presentations for this LiveQuery -->
-    <ul class="space-y-4 p-4 m-2 rounded-md preset-filled-surface-400-600">
+    <ul class="space-y-4">
         {#each lq__event_presentation_obj_li ?? [] as event_presentation_obj (event_presentation_obj.event_presentation_id)}
-            <li class="space-y-2 border border-gray-200 p-2 rounded-md">
+            <li class="space-y-3 border border-surface-200-800 bg-surface-50-900 p-4 rounded-xl shadow-sm transition-colors duration-200">
                 <div class="float-right space-2 flex flex-row items-center">
                     {#if $ae_loc.trusted_access && $ae_loc.edit_mode}
                         <button
@@ -169,7 +160,7 @@
                     {/if}
                 </div>
 
-                <h4 class="h5 rounded-md p-2 preset-filled-surface-300-700">
+                <h4 class="text-lg font-bold rounded-lg px-3 py-2 bg-surface-100-900 flex flex-wrap items-center gap-2">
                     <span
                         class:hidden={!event_presentation_obj.start_datetime ||
                             $events_loc.pres_mgmt
@@ -215,7 +206,7 @@
                     >
                         {#if (event_presentation_obj?.code || event_presentation_obj?.abstract_code) && !$events_loc.pres_mgmt.hide__presentation_code}
                             <span
-                                class="text-sm text-gray-500 bg-yellow-100 p-1 rounded-md border border-yellow-200"
+                                class="text-xs preset-tonal-warning px-2 py-0.5 rounded-md leading-none"
                                 title="Presentation code {event_presentation_obj?.code} and abstract code {event_presentation_obj?.abstract_code}"
                             >
                                 <span class="fas fa-barcode"></span>
@@ -370,7 +361,7 @@
                             </button>
 
                             <pre
-                                class="whitespace-pre-wrap p-2 bg-gray-100 rounded-md"
+                                class="whitespace-pre-wrap p-3 bg-surface-100-900 rounded-lg text-sm"
                                 class:hidden={$events_sess.pres_mgmt
                                     .show_content__presentation_description !==
                                     event_presentation_obj.event_presentation_id}>{event_presentation_obj.description}</pre>