fix: add page size selector to CardsWithPagination (#253)

* fix: add page size selector to CardsWithPagination

Add an optional pageSizeOptions prop to CardsWithPagination that renders
a "Cards per page" dropdown selector, consistent with the existing
TablePaginationSize pattern used in DataTable.

- New PaginationSize component (standalone, no TanStack Table dependency)
- CardsWithPagination: manage pageSize as state, reset to page 1 on change
- Project databases page: increase default from 6 to 20, add selector [10, 20, 50]
- Projects list page: increase default from 9 to 12, add selector [12, 24, 48]
- Fully backward compatible: without pageSizeOptions, behavior is unchanged

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* fix: address CodeRabbit review feedback

- Validate pageSize in handlePageSizeChange (reject 0/negative/NaN)
- Guard empty pageSizeOptions array from rendering empty selector
- Restore className on PaginationNavigation for backward compatibility
- Add aria-label to SelectTrigger for accessibility on small screens

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* fix(pagination-size): fallback to pageSizeOptions[0] when pageSize not in options

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

* fix(pagination-size): fix pageSize is not defined (placeholder ref)

---------

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/components/wrappers/common/pagination/pagination-size.tsx

@@ -0,0 +1,35 @@
+import { Select, SelectContent, SelectItem, SelectTrigger, SelectValue } from "@/components/ui/select";
+import { cn } from "@/lib/utils";
+
+export type PaginationSizeProps = {
+    className?: string;
+    pageSize: number;
+    onPageSizeChange: (size: number) => void;
+    pageSizeOptions?: number[];
+};
+
+export const PaginationSize = (props: PaginationSizeProps) => {
+    const { className, onPageSizeChange, pageSizeOptions = [10, 20, 30, 40, 50] } = props;
+    const effectivePageSize = pageSizeOptions.includes(props.pageSize) ? props.pageSize : pageSizeOptions[0];
+
+    return (
+        <div className={cn("flex items-center justify-end sm:justify-center space-x-2", className)}>
+            <p className="whitespace-nowrap text-sm font-medium hidden md:block">Cards per page</p>
+            <Select
+                value={`${effectivePageSize}`}
+                onValueChange={(value) => onPageSizeChange(Number(value))}
+            >
+                <SelectTrigger className="h-8 w-[4.5rem]" aria-label="Cards per page">
+                    <SelectValue placeholder={effectivePageSize} />
+                </SelectTrigger>
+                <SelectContent side="top">
+                    {pageSizeOptions.map((size) => (
+                        <SelectItem key={size} value={`${size}`}>
+                            {size}
+                        </SelectItem>
+                    ))}
+                </SelectContent>
+            </Select>
+        </div>
+    );
+};