feat(composite-repository): forward remove_package to writable repos

Resolve the phase-b TODO by adding an as_writable_repository_interface_mut
downcast helper on RepositoryInterface, mirroring PHP's instanceof
WritableRepositoryInterface check, and propagate inner errors.

1 files changed, 6 insertions, 0 deletions

diff --git a/crates/shirabe/src/repository/repository_interface.rs b/crates/shirabe/src/repository/repository_interface.rs
index 249bd85..e3a5548 100644
--- a/crates/shirabe/src/repository/repository_interface.rs
+++ b/crates/shirabe/src/repository/repository_interface.rs
@@ -111,6 +111,12 @@ pub trait RepositoryInterface: Countable + std::fmt::Debug {
         None
     }
 
+    fn as_writable_repository_interface_mut(
+        &mut self,
+    ) -> Option<&mut dyn crate::repository::WritableRepositoryInterface> {
+        None
+    }
+
     fn as_any(&self) -> &dyn std::any::Any;
 
     /// Injects this repository's own weak handle so that `add_package` can wire package ->