feat: add CLAUDE_CODE_OAUTH_TOKEN support for subscription auth

[safrano9999]

Summary

• Passes CLAUDE_CODE_OAUTH_TOKEN env var through docker-compose.yml so subscription users can authenticate without an API key
• Documents the new variable in .env.example with usage instructions
• Enables users who authenticate via claude auth (CLI login) to use the wrapper in Docker/Podman

Test plan

• Set CLAUDE_CODE_OAUTH_TOKEN in .env and verify wrapper authenticates successfully
• Verify wrapper still works with ANTHROPIC_API_KEY (no regression)
• Verify container starts without either token set (graceful fallback)

🤖 Generated with Claude Code

[safrano9999]

Feature idea: OAuth token rotation on rate limit

Building on this PR's CLAUDE_CODE_OAUTH_TOKEN support — it would be useful to support multiple tokens with automatic rotation when hitting rate limits.

Concept:

• Support numbered env vars: CLAUDE_CODE_OAUTH_TOKEN_1, CLAUDE_CODE_OAUTH_TOKEN_2, ..., CLAUDE_CODE_OAUTH_TOKEN_N
• On a rate limit error (429), automatically rotate to the next token
• When reaching the last token, wrap around to _1 (round-robin)
• Fall back to current single CLAUDE_CODE_OAUTH_TOKEN behavior when no numbered vars are set

This would allow users with multiple Claude subscriptions to pool their rate limits without needing multiple wrapper instances or external load balancing.