fix(cli): properly pass directory context in attach command

[Jkker]

This PR fixes an issue where the attach command would not correctly pass the directory context to the server, resulting in the TUI session running in a default context instead of the specified or current directory.

Changes:

• Update AttachCommand in attach.ts to resolve the directory (defaulting to process.cwd()) and pass it to tui.
• Update tui signature in app.tsx to accept and propagate the directory parameter.
• Update SDKProvider in sdk.tsx to initialize the client with the directory context.
• Add build-fullstack.ts and install-systemd-service.sh scripts to support local fullstack development and deployment.
• Add scalar documentation support.