[datacas]

Closes #469

Summary

• Found the string-valued evidence path from plan_projection raises AttributeError on a non-object evidence item and loses a finished stage's report #469: normalize_attempts stores the reported attempts verbatim in attempts_normalized, and plan_projection blanked attempts but not attempts_normalized, so clean reached an evidence string and called .items() on its characters.
• plan_projection no longer persists attempts_normalized (it carried raw prose and output), ignores non-object evidence entries, and projects a non-list items as empty.
• Documents the rule in docs/execution-plan.md. docs/ROADMAP_V2.md already lists plan_projection raises AttributeError on a non-object evidence item and loses a finished stage's report #469 in M1.

Tests

• test_projection_drops_raw_normalized_attempts and test_projection_ignores_prose_evidence_entries (string, mixed and non-list evidence; non-list items); both fail without the fix.
• tests/test_verification_decisions.py and tests/test_cycle_history.py pass locally.

Supersedes #473, which could not be updated in place after a rebase.