WIP: feature/SSH

[alexanderbh]

Adds an Anathema SSH server that can serve Anathema apps to client SSH connections.

No breaking changes to existing code.

Changes to exisiting code

• Adds a new way to create a Backend which takes in the "output"/Writer. So it is not hardcoded to stdout.
• Added more modifier keys to the Key event (maybe needs to be mapped from crossterm as well)

New code

• Added a feature "ssh" for this. Not sure if this is needed since you just don't use the SSH server if you don't need it
• anathema-ssh crate which exposes the AnathemaSSHServer and SSHBackend
• SSHBackend is a think wrapper on TuiBackend but instead of reading events from crossterm (stdin) it directly pop events from the event queue
• AnathemaSSHServer takes in a "runtime factory" which is a function that will start the runtime. This is called for each new client.
  • It is therefore the AnathemaSSHServer that instantiates the SSHBackend for each client. It will hook it up with the SSH sesession. The runtime factory then get's the new SSHBackend instance.

Demo:

Screen.Recording.2025-07-16.at.19.28.01.mov