Implement REUSE-WP-0012 federation scale and intent alignment

Add hub sync and report cohorts CLI commands with pytest coverage, document
sibling index publish contract and hub hardening path, align INTENT layout,
raise external evidence on three registry entries, and close gap priorities
19-23 (priority 18 deferred on sibling index blocks).

tools/README.md

@@ -98,10 +98,27 @@ reuse-surface hub status
 reuse-surface hub list
 reuse-surface hub register --repo state-hub --url https://.../capabilities.yaml
 reuse-surface hub update --repo state-hub --enabled true
+reuse-surface hub sync --merge
+reuse-surface hub sync --dry-run
 ```
 
 Run the service locally: `REUSE_SURFACE_TOKEN=dev-token reuse-surface serve`
 
+### report cohorts
+
+Export capability cohorts for planning or implementation reuse decisions.
+
+```bash
+reuse-surface report cohorts
+reuse-surface report cohorts --planning-min D5 --availability-max A1
+reuse-surface report cohorts --implementation-min A4
+reuse-surface report cohorts --format json
+```
+
+Planning preset (`--planning-min`) sets discovery minimum and defaults
+`availability-max` to `A1`. Implementation preset (`--implementation-min`) sets
+availability minimum. Output is Markdown (default) or JSON.
+
 ## Export format
 
 The export bundle includes:
@@ -122,6 +139,8 @@ Stable IDs and maturity fields are preserved for agent consumption (UC-RS-019).
 | Detect overlap | `reuse-surface overlaps` |
 | Publish catalog | `reuse-surface catalog` |
 | Compose federation | `reuse-surface federation compose` |
+| Sync federation manifest from hub | `reuse-surface hub sync` |
+| Planning cohort export | `reuse-surface report cohorts` |
 | Relation graph | `reuse-surface graph` |
 
 ## Related use cases