Implements the plan at
docs/plans/2026-04-20-003-refactor-unify-run-vocabulary-metadata-plan.md.
- Rename RunRecord to RunSpec and RunProjection.run to .spec everywhere
in Rust source, tests, helpers, test names, and error messages.
- Introduce SerializableProjection wrapper that trims bulky node text
fields (prompt, response, diff, stdout, stderr) for run.json snapshots.
- Collapse metadata-branch and CLI export to one RunDump::from_projection
builder emitting run.json + graph.fabro + stages/{stage_id}/... and
drop legacy top-level start/status/checkpoint/sandbox/retro/conclusion
split files.
- Replace MetadataStore::write_checkpoint with write_snapshot returning
the commit SHA; add read_run_projection/read_run_spec; demote
read_checkpoint/read_start_record to projection-field extractors.
- Switch fork, rewind, rebuild_meta, CLI rewind recovery, and retro
upload to read the unified projection layout.
- Add additive query methods on RunSpec and RunProjection.
Serde-level `alias = "spec"` shim dropped; `rename = "run"` retained to
keep the server API wire format stable per the plan's scope boundary.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
