fix(docker): pin base images and suppress apt prompts
Dockerfile.anthropic-proxy:
- Pin rust:latest → rust:1.92.0
- Pin debian:latest → debian:trixie-slim (Debian 13)
- Add DEBIAN_FRONTEND=noninteractive
Dockerfile:
- Add DEBIAN_FRONTEND=noninteractive
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Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>