feat(cli): add open-reuse validate and register portfolio integrations

Implement Integration Definition validator CLI with schema and index checks,
pytest suite, and CI workflow. Register open-cmis-tck and issue-core-gitea in
the integration index.

Closes OPEN-WP-0003 and OPEN-WP-0004.

registry/README.md

@@ -132,14 +132,35 @@ Prove Value
 5. Set `schema_version: open-reuse.integration.v0.1`.
 6. Add a row to `registry/indexes/integrations.yaml` with `id`, `path`, `repo`,
    `reuse_mode`, and `upstream` summary.
-7. Validate manually (checklist below) before setting `status: active`.
+7. Run `open-reuse validate --repos-base <portfolio-root>` before setting
+   `status: active`.
 
 Early adopters may use `schema_version: open-reuse.integration.v1`; the schema
 accepts both. New entries should use v0.1.
 
+## Automated validation
+
+Primary validation path:
+
+```bash
+# Install (from repo root)
+python -m pip install -e ".[dev]"
+
+# Validate local definitions and registry index
+open-reuse validate
+
+# Validate index rows against consuming-repo definitions
+open-reuse validate --repos-base /home/worsch
+
+# Treat promotion-gate warnings as failures (CI default for strict checks)
+open-reuse validate --repos-base /home/worsch --fail-on-warnings
+```
+
+CI runs `open-reuse validate --indexed-only` on every push to `main`.
+
 ## Manual validation checklist
 
-Use until an automated CLI validator ships.
+Fallback when the CLI is unavailable.
 
 ### Required fields
 
@@ -174,14 +195,17 @@ Update actions: `ignore`, `monitor-only`, `open-issue`, `open-update-proposal`,
 - [ ] `reuse_mode` matches `reuse.primary_reuse_mode` in the definition
 - [ ] `upstream.name` matches the definition
 
-## Reference integration
+## Reference integrations
 
-`markitect-quarkdown` provides the first real-world adapter integration:
+| ID | Repo | Reuse mode | Definition path |
+| -- | ---- | ---------- | --------------- |
+| `markitect-quarkdown` | markitect-quarkdown | adapter | `integration/quarkdown.integration.yaml` |
+| `open-cmis-tck` | open-cmis-tck | adapter | `integration/opencmis-tck.integration.yaml` |
+| `issue-core-gitea` | issue-core | adapter | `integration/gitea-backend.integration.yaml` |
 
-- Definition: `markitect-quarkdown/integration/quarkdown.integration.yaml`
-- Index row: `indexes/integrations.yaml` → `markitect-quarkdown`
-
-Use it as a worked example for adapter + cli-boundary reuse.
+`markitect-quarkdown` is the primary worked example for adapter + cli-boundary
+reuse. `open-cmis-tck` illustrates cli-boundary orchestration of an upstream
+test harness. `issue-core-gitea` illustrates a remote API backend adapter.
 
 ## Capability registry