IB-WP-0014: archive-list, restore, retention annotation, docs (T03-T05)

Round out IB-WP-0014 with the remaining archive operations and docs.

- restore_archive() and `infospace-bench restore <pkg> --target <dir>` round-trip
  a finalized package's bytes back to disk. Refuses to overwrite a non-empty
  target unless --force. --from <infospace-root> resolves the store location.
- archive-list CLI with --with-retention flag; annotate_retention() opens the
  per-infospace registry and joins each record with its current retention
  state (effective class, expires, holds, eligibility).
- docs/archive-integration.md covers when to archive, the include set,
  retention classes, storage layout, credentials policy, and the explicit
  non-goal that S3/git backends live in artifact-store.
- SCOPE.md cross-links the new doc.
- Workplan flipped to status: done. Full pytest suite: 72 passed.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

src/infospace_bench/__init__.py

@@ -1,4 +1,11 @@
-from .archive import ArchiveRecord, archive_infospace, list_archives
+from .archive import (
+    ArchiveRecord,
+    RestoredArchive,
+    annotate_retention,
+    archive_infospace,
+    list_archives,
+    restore_archive,
+)
 from .errors import InfospaceError
 from .evaluation import EntityEvaluation, EvaluationSnapshot, MetricValue, ScoreEntry
 from .engine import (
@@ -43,6 +50,7 @@ from .workflow import load_workflows, plan_workflow, run_workflow
 __all__ = [
     "ArchiveRecord",
     "DisciplineBinding",
+    "RestoredArchive",
     "EntityEvaluation",
     "EvaluationSnapshot",
     "Infospace",
@@ -61,6 +69,7 @@ __all__ = [
     "TopicConfig",
     "ViabilityThreshold",
     "add_artifact",
+    "annotate_retention",
     "append_to_history",
     "archive_infospace",
     "create_infospace",
@@ -79,6 +88,7 @@ __all__ = [
     "read_snapshot",
     "record_check_results",
     "register_artifact",
+    "restore_archive",
     "load_workflows",
     "plan_workflow",
     "run_workflow",