projection::project_stage was the last yaml_legacy reader in pipeline_state.
Drop the read_content+parse_front_matter detour for the "7_frozen" case and
always default resume_to to Stage::Coding. The YAML write side in apply.rs
goes in stage 7.
Story 934 (sibling refactor) will replace Stage::Frozen-with-payload with a
frozen flag orthogonal to Stage, so a story frozen in Qa stays in Stage::Qa
rather than encoding a "where to resume" target. After 934 lands the
resume_to payload disappears entirely.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>