refactor(phase-c): share PlatformRepository and RepositorySet via handles

PHP shares a single PlatformRepository by reference across the RepositorySet,
createRequest, VersionSelector, and (in show) the installed repository. The
port worked with owned values / &mut, so it could not share: create_repository_set
silently dropped the platform repo from the pool (PlatformRepository is not
Clone), show rebuilt a fresh PlatformRepository per use, and the package
discovery / show version selectors were stubbed because VersionSelector wanted
an owned RepositorySet.

Thread the existing PlatformRepositoryHandle (Rc<RefCell<PlatformRepository>>)
through installer.rs and show, restoring the RootPackageRepository + platform
repo registration and implementing same_repository via RepositoryInterfaceHandle
ptr_eq. Hold package-discovery repos as a shared RepositoryInterfaceHandle, and
share RepositorySet as Rc<RefCell<RepositorySet>> in the set caches and
VersionSelector (which only reads it), unblocking both stubbed selector sites
and dropping show's placeholder set.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

1 files changed, 7 insertions, 4 deletions

diff --git a/crates/shirabe/src/command/init_command.rs b/crates/shirabe/src/command/init_command.rs
index eabe6e2..5a3c71b 100644
--- a/crates/shirabe/src/command/init_command.rs
+++ b/crates/shirabe/src/command/init_command.rs
@@ -44,13 +44,14 @@ pub struct InitCommand {
 }
 
 impl PackageDiscoveryTrait for InitCommand {
-    fn get_repos_mut(&mut self) -> &mut Option<CompositeRepository> {
+    fn get_repos_mut(&mut self) -> &mut Option<crate::repository::RepositoryInterfaceHandle> {
         todo!()
     }
 
     fn get_repository_sets_mut(
         &mut self,
-    ) -> &mut IndexMap<String, crate::repository::RepositorySet> {
+    ) -> &mut IndexMap<String, std::rc::Rc<std::cell::RefCell<crate::repository::RepositorySet>>>
+    {
         todo!()
     }
 
@@ -512,7 +513,9 @@ impl InitCommand {
                 )?);
             }
 
-            *self.get_repos_mut() = Some(CompositeRepository::new(repos));
+            *self.get_repos_mut() = Some(crate::repository::RepositoryInterfaceHandle::new(
+                CompositeRepository::new(repos),
+            ));
             // unset($repos, $config, $repositories);
         }
 
@@ -746,7 +749,7 @@ impl InitCommand {
         io.write_error3("\nDefine your dependencies.\n", true, io_interface::NORMAL);
 
         // prepare to resolve dependencies
-        let repos = self.get_repos();
+        let _repos = self.get_repos();
         let preferred_stability =
             if let Some(s) = minimum_stability_default.clone().filter(|s| !s.is_empty()) {
                 s