feat: Shared server environment variables

[ShadowArcanist]

Fixes

• [Enhancement]: Environment variables for each server that are auto-added to each application deployed on it #7738

Changes

1. Added Server based as new type of shared variable -> user can create a new variable from /shared-variables/server/{server_uuid} and use them on application or services like {{server.ENV_NAME}}
2. Added COOLIFY_SERVER_UUID and COOLIFY_SERVER_NAME as predefined env (user cannot edit these env manually similar to other predefined env like COOLIFY_CONTAINER_NAME ) but can use them on application like {{server.COOLIFY_SERVER_UUID}} and {{server.COOLIFY_SERVER_NAME}}

server-env.mov

Notes

1. While using build server the destination server env will be used for both build and runtime
2. While deploying an application to multiple servers, the server env associated with each respective server will be used (best usecase for this is letting know the application which server it is actually running on -- helpful for debug)
3. Server env will be available at build time ("Available at Built Time" option must be enabled for this -- enabled by default)
4. If you downgrade to a previous version then all shared server env value will become the name of the env like ({{server.EnvName}}={{server.EnvName}})
5. API routes for server env were not added on this PR
6. We have a post on our discord community related to this PR: https://discord.com/channels/459365938081431553/1452756247479582841 (it's an interesting discussion!)
7. I don't know PHP so all the changes are done by AI, but tested the changes locally and a VPS (also tested on both fresh install and already existing Coolify instance).

Testing

• It is bit hard to test multi server deployments locally and bit hard to test upgrade/downgrade behavior so I was building the coolify image on Github actions (https://github.com/ShadowArcanist/coolify-dev/actions/workflows/coolify-production-build.yml) and used ghcr.io/shadowarcanist/coolify-dev:latest to test it.
• Tested using server env on one click service (umami), applications (Dockerfile, docker image), application using a build server, multi server deployments.

/claim #7738

[github-actions]

Hi @ShadowArcanist! 👋

It appears to us that you are adding a new feature to Coolify.
We kindly ask you to also update the Coolify Documentation to include information about this new feature.
This will help ensure that our documentation remains accurate and up-to-date for all users.

Coolify Docs Repository: https://github.com/coollabsio/coolify-docs
How to Contribute to the Docs: https://coolify.io/docs/get-started/contribute/documentation

[pkpio]

@andrasbacsai would you please take a look at this?

This would save me on month's of headache and also pay the bounty I placed on it.