FE-1267: Record controller takeovers in comparison evidence

[kostandinang]

Why

Comparison reports could describe a controller takeover that was absent from the immutable attempt's intervention list, leaving publication validity unsupported.

What

Require a separately captured controller-intervention ledger when retaining an execution attempt and reject retention unless it exactly matches the attempt. The comparison procedure now records takeovers immediately and derives its visible summary from that ledger.

How to test

1. Run npm test -- src/dev/execution-comparison/__tests__/artifact-contract.test.ts and confirm a mismatched ledger is rejected.
2. Run npm test -- src/dev/execution-comparison/__tests__/operator-cli.test.ts and confirm attempt retention requires the ledger.

[kostandinang]

• FE-1267: Record controller takeovers in comparison evidence #379 👈 (View in Graphite)
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[cursor]

PR Summary

Low Risk
Scoped to dev execution-comparison tooling and operator prompts; tightens evidence validation without changing product runtime behavior.

Overview
Closes a gap where comparison reports could describe controller takeovers that were not reflected in immutable attempt evidence.

Procedure: compare-execution.md now requires logging every controller takeover immediately to <attempt-staging>/intervention-ledger.json (schema version 1, mechanical interventions with index/kind/description/timestamp). Visible-interaction summaries must come from that ledger; unledgered takeovers are not allowed.

Retention: retain-attempt gains a required --intervention-ledger flag. Before writing an attempt, the operator loads the ledger and runs assertExecutionAttemptInterventionLedger, which rejects invalid ledgers or any mismatch with the attempt’s interventions list.

Contract: Adds ExecutionInterventionLedger and assertExecutionAttemptInterventionLedger in artifact-contract.ts, plus unit/CLI tests for mismatch rejection and the missing-flag error.

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