Add public repository interfaces and subclassable adapter CRUD API.

Define split JSON and object repository ABCs, promote adapter methods to public CRUD, add example domain repositories, modernize interface stubs, and make the package installable for tests.

Co-authored-by: Cursor <[email protected]>

python_repositories/interfaces/__init__.py

@@ -2,8 +2,16 @@ from .connection_aware_interface import (
     ConnectionAwareInterface as ConnectionAwareInterface,
 )
 from .context_aware_interface import ContextAwareInterface as ContextAwareInterface
+from .json_repository_interface import (
+    JsonRepositoryInterface as JsonRepositoryInterface,
+)
+from .object_repository_interface import (
+    ObjectRepositoryInterface as ObjectRepositoryInterface,
+)
 
 __all__ = [
     "ConnectionAwareInterface",
     "ContextAwareInterface",
+    "JsonRepositoryInterface",
+    "ObjectRepositoryInterface",
 ]