Change encryption from opt-in (-e) to opt-out (-E/--no-encrypt).
Add argument preprocessing to auto-insert "create" command when
file path is detected, allowing `fpaste file.txt` shortcut.
-e/--encrypt flag encrypts content with AES-256-GCM before upload.
Key is appended to URL fragment (#...), never sent to server.
Auto-detects key fragment on retrieval and decrypts locally.