Update all dependencies

Notable upgrades:
- anthropic 0.67 → 0.83
- fastapi 0.116 → 0.129
- mangum 0.19 → 0.21
- boto3/botocore 1.40 → 1.42
- aiohttp 3.12 → 3.13

All 91 tests pass.

🤖 Generated by LLM (Claude, via OpenClaw)

Author: mattgodbolt-molty