Add interactive CLI flows (use Inquirer, e.g. fw init)

[galligan]

Context

We want interactive CLI flows for tasks like fw init.

Proposal

• Use Inquirer for interactive prompts (text/confirm/select) in the CLI.
• Start with a fw init flow to bootstrap config (repos, defaults, optional Graphite).

Notes

• Keep prompts minimal and skippable for non-interactive usage.
• Follow existing config conventions (user + project config).