fix: resolve all biomaly lint errors and warnings across CMS

- Fix CSS parser config (tailwindDirectives enabled)
- Fix noDangerouslySetInnerHtml via SanitizedHtml component
- Fix useExhaustiveDependencies in catalog-manager-dialog
- Fix noArrayIndexKey across 26 files (stable keys)
- Fix SVG a11y (titles, roles, aria-labels)
- Fix label/input associations (htmlFor/id pairs)
- Fix static element interactions (role + keyboard support)
- Fix noImgElement, noDescendingSpecificity (disabled - external Habbo URLs)
- Fix noNonNullAssertion, useTemplate, unused vars/imports
- Add SanitizedHtml shared component
- Migrate biome.json to 2.5.4 schema

src/lib/services/catalog-tree.ts

@@ -70,7 +70,7 @@ export async function getTreeFlat(): Promise<TreeNode[]> {
 	const depthCache = new Map<number, number>();
 
 	function computeDepth(pageId: number): number {
-		if (depthCache.has(pageId)) return depthCache.get(pageId)!;
+		if (depthCache.has(pageId)) return depthCache.get(pageId) ?? 0;
 		const page = pageMap.get(pageId);
 		const parentId = page ? toInt(page.parentId, -1) : -1;
 		if (!page || parentId <= 0) {