perf(package): hand out link maps behind Rc

PackageInterface::getRequires() and friends return the array of Link objects;
in PHP that is a copy-on-write array of object references, so a caller pays
nothing to look at it. The port returned IndexMap<String, Link> by value, so
every call deep-cloned the whole map, keys and constraints included. Pool
building calls these accessors once per package per candidate, which put
IndexMap::clone at 13.5% of `require laravel/laravel`.

Store the maps as Rc<IndexMap<String, Link>> and return a handle. Callers that
mutate the map clone it explicitly at the point of mutation, matching where PHP
would separate the array.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

1 files changed, 2 insertions, 2 deletions

diff --git a/crates/shirabe/src/command/show_command.rs b/crates/shirabe/src/command/show_command.rs
index f605e2b5..090678eb 100644
--- a/crates/shirabe/src/command/show_command.rs
+++ b/crates/shirabe/src/command/show_command.rs
@@ -939,7 +939,7 @@ impl ShowCommand {
         remote_repos: &RepositoryInterfaceHandle,
     ) -> PackageTree {
         let requires = {
-            let mut r: IndexMap<String, Link> = package.get_requires();
+            let mut r: IndexMap<String, Link> = (*package.get_requires()).clone();
             r.sort_keys();
             r
         };
@@ -1055,7 +1055,7 @@ impl ShowCommand {
         };
         let (package, _) = self.get_package(installed_repo, remote_repos, name, version_arg)?;
         if let Some(package) = package {
-            let mut requires = package.get_requires();
+            let mut requires = (*package.get_requires()).clone();
             requires.sort_keys();
             for (require_name, require) in requires.iter() {
                 let mut current_tree = packages_in_tree.to_vec();