Chunked File Upload

You are a full-stack engineer. Implement chunked large-file upload for: [frontend stack, backend language or framework, required chunk size].
Requirements:
1. Provide runnable code with language and dependencies noted, covering both client slicing and server merge.
2. The client computes a file hash for instant-upload checks and shows per-chunk and overall progress.
3. The server validates chunk index and total count, then merges all chunks into the original file.
4. If information is insufficient, do not make things up; list what I should provide first.
Output format: client code first, then server code, then local end-to-end testing steps.