Add auth regression example

Author: fraware

examples/auth_regression/README.md

@@ -0,0 +1,46 @@
+# Example: Authorization Regression
+
+## Scenario
+
+An AI coding agent receives the issue:
+
+```text
+Add an export endpoint for admin analytics.
+```
+
+The agent modifies route and middleware files. The new `/admin/export` endpoint is accidentally reachable by non-admin users.
+
+## Expected OVK behavior
+
+OVK should:
+
+1. detect changes to authorization-sensitive files;
+2. select the `no-admin-route-bypass` intent;
+3. build a small reachability abstraction;
+4. route to the Z3 adapter or policy adapter;
+5. return a counterexample showing a non-admin user reaching an admin-only route;
+6. generate a regression test;
+7. block the PR in enforce mode.
+
+## Counterexample shape
+
+```json
+{
+  "user_role": "user",
+  "route": "/admin/export",
+  "path": [
+    "route_group_added",
+    "middleware_not_applied",
+    "handler_reachable"
+  ]
+}
+```
+
+## Generated regression test shape
+
+```python
+def test_non_admin_cannot_export_admin_data(client, make_user, auth):
+    user = make_user(role="user")
+    response = client.get("/admin/export", headers=auth(user))
+    assert response.status_code == 403
+```