File Upload System

PROJECT CONTEXT:
I am building an app where users upload files (images or documents) that must be stored and displayed.

GOAL:
Implement working upload, validation, storage, listing, and deletion of user files.

REQUIREMENTS:
- File picker with type and size validation
- Upload progress and error states
- Files actually stored (server storage or base64/db for MVP)
- Uploaded files listed and viewable after refresh
- Delete with confirmation that removes the stored file

CONSTRAINTS:
- A preview from createObjectURL is not an upload - files must persist
- Enforce type/size limits on the backend too
- Every file must be linked to its owner

DEFINITION OF DONE:
- A file uploads with visible progress
- It appears in the list and survives refresh
- Invalid type/size is rejected with a clear message
- Delete removes it permanently

COMMON FAILURES TO AVOID:
- Local preview shown as if uploaded, gone after refresh
- No size/type validation on the server
- Uploads that overwrite files with identical names
- Broken image links because paths/URLs are wrong