Add external asset hosting for Chromatic image rendering

Migrate Gitea remotes to git.tensordesign.com.au. Add assetUrl() utility
that resolves image paths from Gitea ParsonsAssets repo when
STORYBOOK_ASSET_BASE is set, enabling images on Chromatic-published
Storybook while keeping local dev unchanged via staticDirs.

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

src/utils/assetUrl.ts

@@ -0,0 +1,10 @@
+/**
+ * Resolves a static asset path. In local dev the path is served by Storybook's
+ * staticDirs; when STORYBOOK_ASSET_BASE is set (e.g. Chromatic builds) it
+ * prepends the external host URL so images load from Gitea.
+ */
+export const assetUrl = (path: string): string => {
+  const base =
+    typeof import.meta !== 'undefined' ? (import.meta.env?.STORYBOOK_ASSET_BASE ?? '') : '';
+  return `${base}${path}`;
+};