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cc @stripe/developer-products

Summary

This PR adds the ability to manage multiple logged-in Stripe accounts in the CLI.

Related to #1135.

New commands:

• stripe login list - Lists all logged-in accounts, indicating which is currently active
• stripe login switch <account> - Switches to a different logged-in account

How it works:

The CLI stores each logged-in account as a "profile" in the config file. The [default] profile is always the active one. When switching accounts:

1. Current [default] is backed up using its display name as the key
2. Target profile is copied to [default]
3. Old target key is removed to keep config clean

When logging into a new account, the previous account's credentials are automatically preserved as a backup profile.

Key changes:

• Added CopyProfile, ListProfiles, SwitchProfile methods to Config
• Added login list and login switch subcommands
• Fixed several bugs in profile management (nil panic in RemoveProfile, viper key deletion not persisting)
• Added comprehensive tests for new functionality

Example usage:

# List all logged-in accounts
$ stripe login list
Available profiles:
  * Production Account (active)
    Test Account
    Acme Corp

# Switch to a different account
$ stripe login switch "Test Account"
Switched to profile: Test Account

Tests:

• TestCopyProfile / TestCopyProfileErrors
• TestListProfiles / TestListProfilesEmpty
• TestRemoveProfile
• TestSwitchProfile