Anthropic Provider - Claude OAuth Login for Pro/Max Subscription Support

[travisdieckmann]

I currently have a Claude max subscription and I'm unable to get an API key to use with Amplifier.

Propose one of the following:

• Update the documentation to inform how we can use the monthly subscription to get an API key
• Update the documentation with instructions on how to configure the Anthropic provider to use the Pro/Max subscription
• Update the Anthropic provider to use the default $HOME/.claude/.credentials.json OAuth credentials
• Add an OAuth login flow to the Anthropic Provider setup as an alternative to API Key

[josephjorgensen]

Similarly, I frequently use AWS Bedrock for Claude Code, would love to do the same here like I did with amplifier-claude