Phase 1.2: Authentication commands (login, logout, whoami)

[omattsson]

Overview

Implement interactive login, logout, and credential management.

Tasks

• stackctl login — prompt for username/password, call POST /api/v1/auth/login, store JWT
• stackctl logout — clear stored token for current context
• stackctl whoami — call GET /api/v1/auth/me, display user info
• Token storage in ~/.stackmanager/tokens/<context>.json with expiry metadata (file perms 0600)
• Auto-detect expired tokens; print clear error prompting re-login
• API key auth via config set api-key sk_... — skips JWT when present

Acceptance Criteria

• Full login/logout cycle works against make dev backend
• stackctl whoami shows current user after login
• API key auth works when configured
• Expired token produces a clear error message

Depends On

• Phase 1.1: Scaffold CLI module, config, and HTTP client #1

API Endpoints

Method	Path	Description
POST	/api/v1/auth/login	{ username, password } → { token }
GET	/api/v1/auth/me	Current user info