Convert /-/actions.json from top-level array to object

/-/actions.json now returns {"ok": true, "actions": [...]} instead of a
bare JSON array, so the response can grow additional keys without a
breaking change. The debug_actions.html template reads data.actions,
and the endpoint is now documented in docs/introspection.rst.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01GrHZSypDfMnym1tM5XJAFZ

docs/introspection.rst

@@ -155,6 +155,30 @@ Shows currently attached databases. `Databases example <https://latest.datasette
         ]
     }
 
+.. _JsonDataView_actions:
+
+/-/actions
+----------
+
+Shows all actions registered with the permission system, including those added by plugins. Requires the ``permissions-debug`` permission.
+
+.. code-block:: json
+
+    {
+        "ok": true,
+        "actions": [
+            {
+                "name": "view-instance",
+                "abbr": "vi",
+                "description": "View Datasette instance",
+                "takes_parent": false,
+                "takes_child": false,
+                "resource_class": null,
+                "also_requires": null
+            }
+        ]
+    }
+
 .. _JumpView:
 
 /-/jump