Support Amazon Bedrock model IDs and authentication

[that-github-user]

Summary

thinktank should support Amazon Bedrock as a Claude provider. Users with Bedrock access use different model IDs (e.g., anthropic.claude-opus-4-6-v1) and authenticate via AWS credentials rather than Anthropic API keys.

Bedrock model IDs

From https://docs.aws.amazon.com/bedrock/latest/userguide/models-supported.html:

• anthropic.claude-opus-4-6-v1
• anthropic.claude-sonnet-4-6-v1
• anthropic.claude-haiku-4-5-v1
• etc.

What needs to change

Model validation (src/cli.ts)

Currently warns for unknown models but accepts claude-* prefixed IDs. Should also accept anthropic.* prefixed IDs without warning.

Runner (src/runners/claude-code.ts)

Claude Code CLI already supports Bedrock via:

• ANTHROPIC_MODEL env var
• --model flag with Bedrock model IDs
• AWS credential env vars (AWS_ACCESS_KEY_ID, AWS_SECRET_ACCESS_KEY, AWS_REGION)

The runner may need to pass through AWS env vars to the spawned claude processes.

Config (src/utils/config.ts)

Allow model config to accept Bedrock model IDs.

Documentation

• Update README Models section to mention Bedrock IDs
• Update .env.example with AWS credential placeholders

Acceptance criteria

• --model anthropic.claude-opus-4-6-v1 accepted without warning
• AWS env vars passed through to agent processes
• Documentation updated
• Test with Bedrock model ID validation

[that-github-user]

Fixed in #125. Accept anthropic.* Bedrock model IDs in CLI + config. AWS env vars passed through. README + .env.example updated. 11 new tests. Generated by thinktank Opus.