Manage initiative evidence

Output contract: Let the CLI validate and mutate state; preserve its exact result, warnings, publication status, artifacts, and next actions. For suggested actions, pair Shell with the returned Copilot command; honor commandGuidance. If absent, say "Copilot: no verified equivalent"; never invent a slash command.

Boundary: no Story required; cwd=opened Git root or verified repositoryPath from singularity-flow workspace current --json; refuse if neither resolves; never search $HOME/parents.

For listing, run singularity-flow initiative evidence list [CHECK-ID] --json and show hash, phase, check, assurance, observation time, freshness, source, and registrar identity.

For registration:

1. Show the active checklist contract with /sf-initiative-checklist.
2. Require the contributor to explicitly choose machine-verified, system-verified, human-approved, or presence-only and identify the source.
3. Preview the phase, checklist item, source, assurance, verification method, applicability decision, reason, and superseded hashes.
4. Run singularity-flow initiative evidence add <CHECK-ID> --assurance <LEVEL> with the supplied --path, --url, --external-id, --observed-state, --source-version, --verification, --decision, --reason, and repeatable --supersedes values.
5. Report the content hash, committed evidence copy, commit, and push.

Never infer higher assurance from a URL or file. Every registration is an append-only lifecycle event and must be committed and pushed.