fix(dashboard) Standardize heading levels for consistent hierarchy (#13861)

## Summary

**What** — What changes are introduced in this PR?

This PR standardizes heading levels across dashboard components to maintain proper semantic HTML hierarchy.

**Why** — Why are these changes relevant or necessary?  

*Please provide answer here*

**How** — How have these changes been implemented?

- Added optional `headingLevel` prop `"h1" | "h2" | "h3"` to `DataTable` component with default value of `"h1"`

- Modified `Heading` component usage to explicitly specify the appropriate level based on context

**Testing** — How have these changes been tested, or how can the reviewer test the feature?

*Please provide answer here*

---

## Checklist

Please ensure the following before requesting a review:

- [x] I have added a **changeset** for this PR
    - Every non-breaking change should be marked as a **patch**
    - To add a changeset, run `yarn changeset` and follow the prompts
- [ ] The changes are covered by relevant **tests**
- [x] I have verified the code works as intended locally
- [ ] I have linked the related issue(s) if applicable

packages/admin/dashboard/src/components/data-table/data-table.tsx

@@ -77,6 +77,7 @@ interface DataTableProps<TData> {
   rowHref?: (row: TData) => string
   emptyState?: DataTableEmptyStateProps
   heading?: string
+  headingLevel?: "h1" | "h2" | "h3"
   subHeading?: string
   prefix?: string
   pageSize?: number
@@ -117,6 +118,7 @@ export const DataTable = <TData,>({
   enableFilterMenu,
   rowHref,
   heading,
+  headingLevel = "h1",
   subHeading,
   prefix,
   pageSize = 10,
@@ -384,7 +386,7 @@ export const DataTable = <TData,>({
           <div className="flex items-center gap-x-4">
             {shouldRenderHeading && (
               <div>
-                {heading && <Heading>{heading}</Heading>}
+                {heading && <Heading level={headingLevel}>{heading}</Heading>}
                 {subHeading && (
                   <Text size="small" className="text-ui-fg-subtle">
                     {subHeading}