Add source object contract fixture

Author: mdheller

examples/contracts/object.alpha.json

@@ -0,0 +1,21 @@
+{
+  "schema": "sourceos.object-record/v1alpha1",
+  "object_id": "object:alpha",
+  "object_type": "file",
+  "schema_id": "schema:source-object:v1",
+  "schema_version": "v1",
+  "workspace_id": "workspace:default",
+  "profile_id": "profile:local-dev",
+  "owner_identity": "identity:local-user",
+  "created_by_actor": "actor:agent-one",
+  "last_modified_by_actor": "actor:agent-one",
+  "created_at": "2026-05-05T00:00:00Z",
+  "updated_at": "2026-05-05T00:05:00Z",
+  "privacy_class": "work",
+  "sync_visibility": "workspace",
+  "retention_class": "normal",
+  "policy_tags": ["local-first", "mvp"],
+  "provenance": ["event:object-alpha-created"],
+  "state": "active",
+  "content_hash": "sha256:example"
+}