[FEATURE] Export and Import Notes

[Dev-ev-v]

Problem

Notes cannot be exported to the user's device storage, nor can they be imported into doggy-notes. This creates a dependency between the notes and the application.

Proposal

Notes can be exported via download and imported if they follow the correct format.

Use cases

• doggy export
• doggy export
• doggy import <file_path>

Alternatives considered

There are no viable alternatives; this feature is necessary.

Additional context

Notes are added to the user's Downloads folder by default.