docs: seal teaching against the final staged diff

[chtnnh]

Closes #13

Summary

Corrects the documented know-code workflow so teaching is sealed after implementation and staging, against the final intended diff hash.

The previous order told users to run know-code taught before editing. Any subsequent implementation changed the hash and immediately invalidated that seal, creating unnecessary re-sealing and instructions that disagreed with the CLI’s artifact binding.

Documentation updates

• Update the canonical know-code-teach sequence.
• Move the explain-playbook sealing checkpoint to after the final intended diff is staged.
• Align the public skills workflow table with the final-hash requirement.

Verification

• npm run lint
• npm run build:docs
• git diff --check

[cursor]

PR Summary

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