Create standalone browser port of LTX Athena with authenticated native API transport

frontend/lib/generation-input.ts

@@ -0,0 +1,6 @@
+export async function prepareGenerationInput(inputPath: string | null | undefined): Promise<string | null> {
+  if (!inputPath) return null
+  const result = await window.electronAPI.prepareGenerationInput({ path: inputPath })
+  if (!result.success) throw new Error(result.error)
+  return result.path
+}