Feature: save as new, duplicate

[idjohnson]

Description

I often want to show multiple transforms of an idea, or a migration/build out of an idea. To date, I have to export a JSON, do new, and import the JSON which is a hassle. This allows us to now duplicate a server diagram to a new "(copy)" file as well as saving the existing session as a new ID (instead of overwriting the current copy)

I used Gemini 3 Pro to implement (in case you have issues with AI generated code, though I didn't see anything in CONTRIBUTING.md about that)

Related Issue

Fixes #123

Type of Change

• Bug fix
• New feature
• Documentation update
• Performance improvement

Testing

• Tests pass locally
• Added new tests
• Manual testing completed

Screenshots (if applicable)

[stan-smith]

hey @idjohnson thanks for submitting this PR, thanks for being open about the AI generated code.
Not a problem, just obviously we will need to make sure it isn't going to accidentally delete diagrams etc, so I'll need to do some quite extensive testing for this 👍
Cheers, Stan

[idjohnson]

sounds good. I'll be using it on my instance (https://fossflow.tpk.pw/) so I'll do some more real world testing as well.

[stan-smith]

@idjohnson awesome, appreciate it, hope you're the new features since you last looked!
I'll hopefully get it up and running tomorrow, busy weekend.
Cheers,
Stan

[stan-smith]

Hi @idjohnson I am going to be testing this soon, just on holiday at the moment!