Test the Krad graph and CLI contracts

[keys-i]

Closes #3

Motivation

Protect the small public behavior boundary before build functionality is added.

Changes

• test the four-component dependency order
• cover invalid revisions, missing dependencies, and dependency cycles
• parse and verify JSON plan output
• assert missing-source and invalid CLI failures with exit status 1

Verification

• npm test passed: 3 tests, 3 passed, 0 failed
• git diff --check bootstrap..tests passed

Risk and rollback

Tests use only Node's standard library and spawn the local CLI. Roll back by reverting commit 161b3d2.

Stack

Depends on the verifier PR; base: verify. The documentation PR targets this branch.