[UX] Extend dstack login with interactive selection of url and default project

[peterschmidt85]

1. Similar to gh auth login, if the user does not pass --url to dstack login, the command prompts the user to enter it interactively. The default value in this case is https://sky.dstack.ai.

2. If the logged-in user has more than one project, dstack login prompts the user to select a default project using an interactive menu.

3. Similar to dstack project, to explicitly avoid interactive prompts, dstack login now accepts -n/--no (does not change the default project) and -y/--yes (sets the user’s first project as the default).

---

Note

Enhances dstack login with interactive UX and clearer project configuration.

• Interactive URL prompt via rich (UrlPrompt) when --url is omitted; defaults to https://sky.dstack.ai
• Provider selection prompt using questionary when multiple providers and TTY; otherwise requires -p/--provider
• New --yes and --no flags to control default project selection; automatic logic for single project or preserving existing default
• Project config flow: add all projects as non-default, then set a default (auto or via select_default_project); updated console messages
• Tests updated to cover no projects, multi-project with/without prompts, --yes/--no, and single-project auto-default

^{Written by Cursor Bugbot for commit fca3d6e. This will update automatically on new commits. Configure here.}

[cursor]

Cursor Bugbot has reviewed your changes and found 1 potential issue.

^{Bugbot Autofix is OFF. To automatically fix reported issues with Cloud Agents, enable Autofix in the Cursor dashboard.}

[cursor]

Missing confirmation message after interactive project selection

Low Severity

The interactive project selection path (the else branch) successfully configures and saves the selected default project but does not print a confirmation message. All other code paths that set a default project (the --yes flag at lines 193-195 and the auto-default case at lines 224-226) print a "Set [project] project as default at [path]" message. This inconsistency means users who interactively select a project receive no feedback that their selection was applied.