[devcontainers]: Add docker/docker-agent config compatibility layer

Issue: [devcontainers]: Add docker/docker-agent config compatibility layer

Feature: devcontainers
Priority: high
Labels: devcontainers, high-priority, competitive

Description

Docker Engineering shipped docker/docker-agent 2 days ago — an official AI Agent Builder & Runtime that uses a container-based agent definition model. This is Docker entering daax's core territory. daax devcontainers should be importable/exportable to/from docker-agent format so that teams evaluating docker-agent can migrate to daax without rewriting their container configs.

Intel driver: docker/docker-agent (2026-04-05, 2 days old). Docker entering agent runtime space is the biggest competitive signal of the week.

What

Add a compatibility layer that:

1. Parses docker-agent container configuration format
2. Maps docker-agent agent definitions to daax devcontainer specs
3. Exports daax devcontainer configs to docker-agent format

Why

Docker's brand recognition means teams will evaluate docker-agent first. If daax configs are compatible, onboarding from docker-agent is frictionless. Differentiation happens at the hawkeye + nanofuse layer, not the container definition layer.

Definition of Done

• Can import a valid docker-agent YAML config and generate a daax devcontainer spec without manual edits
• Can export a daax devcontainer spec that passes docker-agent validate (or equivalent)
• Round-trip test: import → export → import produces identical configs
• Integration test covers: image spec, env vars, volume mounts, port bindings, tool declarations
• Documentation: migration guide from docker-agent to daax with 3 worked examples

Start by locating the repository's devcontainer configuration handling and confirming the docker-agent configuration schema. Implement import and export coverage for image specs, environment variables, volume mounts, port bindings, and tool declarations. Define done with integration and round-trip tests, docker-agent validation, and a migration guide containing three worked examples.