Harden memU open source workflows

[sairin1202]

Summary

• add a Markdown context harness with raw-data evidence, self-evolve instructions, reviewed patch proposals, and context-pack generation
• add a built-in JSON server, OpenAPI contract, and server/config hardening
• improve open-source readiness with governance docs, CI/security automation, provider docs, examples, and contract tests

Validation

• compileall on focused changed modules during development
• repository docs smoke: 82 no-arg contract tests
• targeted contract smoke suites for server/settings/retrieve/docs paths where local dependencies allowed

Note: uv, pytest, and PATH git are not available in this local shell; GitHub Desktop bundled Git was used for branch, commit, and push.

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