✨(frontend) create utility for media download URL generation

Encapsulate URL base generation logic for media downloads into a reusable
utility function, mirroring the approach used in the API. Improves code
consistency and reduces duplication across frontend components.

src/frontend/src/api/mediaUrl.ts

@@ -0,0 +1,11 @@
+export const mediaUrl = (path: string) => {
+  const origin =
+    import.meta.env.VITE_API_BASE_URL ||
+    (typeof window !== 'undefined' ? window.location.origin : '')
+
+  // Remove leading/trailing slashes from origin/path if it exists
+  const sanitizedOrigin = origin.replace(/\/$/, '')
+  const sanitizedPath = path.replace(/^\//, '')
+
+  return `${sanitizedOrigin}/media/${sanitizedPath}`
+}