Artifacts available at the app level

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**Is your feature request related to a problem? Please describe.**
A clear and concise description of what the problem is. Ex. I'm always frustrated when [...]

I want to be able to share/update artifacts that are accessible to ALL users. Currently artifacts are only available within the session and user scope.

My usecase is being able to inject an artifact within my system prompt for self evolution. A new prompt that is saved as an artifact should be available at the app level so that all users can benefit from it.

**Describe the solution you'd like**
A clear and concise description of what you want to happen.

Allow saving artifacts to be accessible at the App level.

**Describe alternatives you've considered**
A clear and concise description of any alternative solutions or features you've considered.

Callbacks to load files from a bucket and append to system prompt. But theres no straight forward way to inject into the middle of a system prompt (unless you have suggestions) . Artifacts would make it easy with placeholders

**Additional context**
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