Require shared accepted-iteration summaries in Crane updates

[Copilot]

Long-running Crane PRs can drift from the latest accepted iteration, forcing reviewers to reconstruct state from commits, issues, workflow runs, and repo memory. This makes the workflow prompt require one compact accepted-iteration summary reused across every reviewer-facing and state-tracking surface.

• Workflow prompt contract

  • Adds an Accepted Iteration Summary section after verification.
  • Defines required summary fields: iteration status, focus, change bullets, commit/run links, score delta, parity/progress counts, and CI fix attempts.
  • Caps summaries to roughly ten bullets / 1000 characters and points to evidence instead of logs or diffs.

• Existing PR update behavior

  • Requires push-to-pull-request-branch for existing PRs.
  • Also requires an explicit add-comment safe output with the same contentful summary.
  • Prevents relying on the generic push comment as the only reviewer-facing update.

• Shared output surfaces

  • Requires the same facts in:
    • PR body
    • PR comment
    • Migration issue comment
    • Repo-memory iteration history

• Prompt-level coverage

  • Adds a unit test asserting the summary section, shared-source language, required surfaces, and safe outputs are present.

### Accepted Iteration Summary

For every accepted iteration, construct a single shared source summary before updating any output surface.
Reuse this same summary, with the same facts, in the PR body, an explicit PR comment,
the migration issue comment, and the repo-memory iteration history.

[mrjf]

@copilot resolve the merge conflicts in this pull request

[Copilot]

@copilot resolve the merge conflicts in this pull request

Resolved the merge conflicts by merging origin/main and preserving the accepted-iteration summary changes in commit 0be1d7c.