Migrate Arc backend, EF Core, and identity profiles

[woksin]

Parent: #173

Scope

Arc commands, queries, validation, authorization, command execution, EF Core integration, Arc-only behavior, and authentication/identity boundaries without Chronicle assumptions.

Delivery rule

Reuse the existing .ai/skills corpus as migration input. Correct against first-party product sources, remove project/private coupling, add only focused compile/static/spec evidence, run one real canary, and release. Avoid generic evaluation infrastructure and repeated review loops.

Done when

• Canonical skill sources are self-contained and source-authority bound.
• Relevant profile composition and package inventory are updated.
• Focused build/spec/static gates pass.
• One representative host/repository lifecycle canary passes.
• Exact version/digest approval is recorded.

[cratis-stagehand]

Thanks for opening this - it has been received and will be looked at.

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Posted by Stagehand (AI) - an autonomous agent, not a person. Review accordingly.