feat: add page selector dropdown with animated pagination controls

Replace Previous/Next buttons with 5-slot page navigation centered in
pagination bar. Current page becomes a dropdown trigger allowing direct
page jumps. Side slots animate on page transitions.

web/src/lib/components/Pagination.svelte

@@ -1,4 +1,8 @@
 <script lang="ts">
+import { Select } from "bits-ui";
+import { ChevronUp, ChevronDown } from "@lucide/svelte";
+import { fly } from "svelte/transition";
+
 let {
   totalCount,
   offset,
@@ -11,32 +15,148 @@ let {
   onPageChange: (newOffset: number) => void;
 } = $props();
 
+const currentPage = $derived(Math.floor(offset / limit) + 1);
+const totalPages = $derived(Math.ceil(totalCount / limit));
 const start = $derived(offset + 1);
 const end = $derived(Math.min(offset + limit, totalCount));
-const hasPrev = $derived(offset > 0);
-const hasNext = $derived(offset + limit < totalCount);
+
+// Track direction for slide animation
+let prevPage = $state(1);
+let direction = $state(0);
+
+$effect(() => {
+  const page = currentPage;
+  if (page !== prevPage) {
+    direction = page > prevPage ? 1 : -1;
+    prevPage = page;
+  }
+});
+
+// 5 page slots: current-2, current-1, current, current+1, current+2
+const pageSlots = $derived([-2, -1, 0, 1, 2].map((delta) => currentPage + delta));
+
+function isSlotVisible(page: number): boolean {
+  return page >= 1 && page <= totalPages;
+}
+
+function goToPage(page: number) {
+  onPageChange((page - 1) * limit);
+}
+
+// Build items array for the Select dropdown
+const pageItems = $derived(
+  Array.from({ length: totalPages }, (_, i) => ({
+    value: String(i + 1),
+    label: String(i + 1),
+  }))
+);
+
+const selectValue = $derived(String(currentPage));
 </script>
 
-{#if totalCount > 0}
-  <div class="flex items-center justify-between text-sm">
-    <span class="text-muted-foreground">
-      Showing {start}–{end} of {totalCount} courses
-    </span>
-    <div class="flex gap-2">
-      <button
-        disabled={!hasPrev}
-        onclick={() => onPageChange(offset - limit)}
-        class="border border-border bg-card text-foreground rounded-md px-3 py-1.5 text-sm disabled:opacity-40 disabled:cursor-not-allowed hover:bg-muted/50 transition-colors"
-      >
-        Previous
-      </button>
-      <button
-        disabled={!hasNext}
-        onclick={() => onPageChange(offset + limit)}
-        class="border border-border bg-card text-foreground rounded-md px-3 py-1.5 text-sm disabled:opacity-40 disabled:cursor-not-allowed hover:bg-muted/50 transition-colors"
-      >
-        Next
-      </button>
+{#if totalCount > 0 && totalPages > 1}
+  <div class="flex items-center text-sm">
+    <!-- Left zone: result count -->
+    <div class="flex-1">
+      <span class="text-muted-foreground">
+        Showing {start}&ndash;{end} of {totalCount} courses
+      </span>
     </div>
+
+    <!-- Center zone: page buttons -->
+    <div class="flex items-center gap-1">
+      {#key currentPage}
+        {#each pageSlots as page, i (i)}
+          {#if i === 2}
+            <!-- Center slot: current page with dropdown trigger -->
+            <Select.Root
+              type="single"
+              value={selectValue}
+              onValueChange={(v) => {
+                if (v) goToPage(Number(v));
+              }}
+              items={pageItems}
+            >
+              <Select.Trigger
+                class="inline-flex items-center justify-center gap-1 w-auto min-w-9 h-9 px-2.5
+                       rounded-md text-sm font-medium tabular-nums
+                       border border-border bg-card text-foreground
+                       hover:bg-muted/50 active:bg-muted transition-colors
+                       cursor-pointer select-none outline-none
+                       focus-visible:ring-2 focus-visible:ring-ring focus-visible:ring-offset-2 focus-visible:ring-offset-background"
+                aria-label="Page {currentPage} of {totalPages}, click to select page"
+              >
+                <span in:fly={{ x: direction * 20, duration: 200 }}>{currentPage}</span>
+                <ChevronUp class="size-3 text-muted-foreground" />
+              </Select.Trigger>
+              <Select.Portal>
+                <Select.Content
+                  class="border border-border bg-card shadow-md outline-hidden z-50
+                         max-h-72 min-w-16 w-auto
+                         select-none rounded-md p-1
+                         data-[state=open]:animate-in data-[state=closed]:animate-out
+                         data-[state=closed]:fade-out-0 data-[state=open]:fade-in-0
+                         data-[state=closed]:zoom-out-95 data-[state=open]:zoom-in-95
+                         data-[side=top]:slide-in-from-bottom-2
+                         data-[side=bottom]:slide-in-from-top-2"
+                  side="top"
+                  sideOffset={6}
+                >
+                  <Select.ScrollUpButton class="flex w-full items-center justify-center py-0.5">
+                    <ChevronUp class="size-3.5 text-muted-foreground" />
+                  </Select.ScrollUpButton>
+                  <Select.Viewport class="p-0.5">
+                    {#each pageItems as item (item.value)}
+                      <Select.Item
+                        class="rounded-sm outline-hidden flex h-8 w-full select-none items-center
+                               justify-center px-3 text-sm tabular-nums
+                               data-[highlighted]:bg-accent data-[highlighted]:text-accent-foreground
+                               data-[selected]:font-semibold"
+                        value={item.value}
+                        label={item.label}
+                      >
+                        {item.label}
+                      </Select.Item>
+                    {/each}
+                  </Select.Viewport>
+                  <Select.ScrollDownButton class="flex w-full items-center justify-center py-0.5">
+                    <ChevronDown class="size-3.5 text-muted-foreground" />
+                  </Select.ScrollDownButton>
+                </Select.Content>
+              </Select.Portal>
+            </Select.Root>
+          {:else}
+            <!-- Side slot: navigable page button or invisible placeholder -->
+            <button
+              class="inline-flex items-center justify-center w-9 h-9
+                     rounded-md text-sm tabular-nums
+                     text-muted-foreground
+                     hover:bg-muted/50 hover:text-foreground active:bg-muted transition-colors
+                     cursor-pointer select-none
+                     focus-visible:ring-2 focus-visible:ring-ring focus-visible:ring-offset-2 focus-visible:ring-offset-background
+                     {isSlotVisible(page) ? '' : 'invisible pointer-events-none'}"
+              onclick={() => goToPage(page)}
+              aria-label="Go to page {page}"
+              aria-hidden={!isSlotVisible(page)}
+              tabindex={isSlotVisible(page) ? 0 : -1}
+              disabled={!isSlotVisible(page)}
+              in:fly={{ x: direction * 20, duration: 200 }}
+            >
+              {page}
+            </button>
+          {/if}
+        {/each}
+      {/key}
+    </div>
+
+    <!-- Right zone: spacer for centering -->
+    <div class="flex-1"></div>
+  </div>
+{:else if totalCount > 0}
+  <!-- Single page: just show the count, no pagination controls -->
+  <div class="flex items-center text-sm">
+    <span class="text-muted-foreground">
+      Showing {start}&ndash;{end} of {totalCount} courses
+    </span>
   </div>
 {/if}