Add authentication and host configuration to Anthropic proxy

[ThomasK33]

Add authentication and host configuration to Anthropic proxy

This PR adds security and flexibility to the Anthropic proxy:

1. Added authentication support with a custom header token:

   • New authToken option to require authentication
   • Configurable authHeaderName (defaults to "X-AnyClaude-Token")
   • Returns 401 Unauthorized when token doesn't match

2. Added host configuration:

   • New host parameter (defaults to "127.0.0.1")
   • Properly reflects host in returned URL

3. Improved security for the CLI:

   • Generates a random UUID token if none provided
   • Injects token via ANTHROPIC_CUSTOM_HEADERS
   • Reuses existing API keys when available

4. Updated example model name in help text to "openai/gpt-5-mini"

[ThomasK33]

• Add authentication and host configuration to Anthropic proxy #6 👈 (View in Graphite)
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