feat(package): implement PackageInterface accessor layer for Package/CompletePackage/RootPackage

Fill the trait-impl todo!() across the package accessor layer so loaded
packages are actually usable (the ArrayLoader::load path depends on it):

- Package: implement BasePackage/PackageInterface from struct fields and
  existing inherent methods; Display via get_unique_name.
- CompletePackage: delegate PackageInterface to inner Package.
- RootPackage: delegate CompletePackageInterface/PackageInterface to inner
  CompletePackage; RootPackageInterface link setters delegate to Package.

Correct three unfaithful trait signatures found during implementation:

- get_target_dir returns Option<String> (PHP computes a normalized value;
  a borrow cannot represent it, and AliasPackage could not implement &str
  across its aliasOf handle).
- RootPackageInterface link setters take IndexMap<String, Link>, matching
  Package and the real ArrayLoader caller (PHP RootPackage inherits
  Package::setRequires; the Link[] docblock was imprecise).
- get_full_pretty_version takes a DisplayMode enum instead of a raw i64;
  the match is now exhaustive, so it returns String without an error path.

Move mirror conversion to the boundaries: PackageInterface mirror methods
use Vec<Mirror> (the typed form, matching the inherent methods), with
array<->Mirror conversion done by the producer (ComposerRepository) and
consumer (ArrayDumper).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

2 files changed, 10 insertions, 6 deletions

diff --git a/crates/shirabe/src/downloader/file_downloader.rs b/crates/shirabe/src/downloader/file_downloader.rs
index 5b66a9f..55882f7 100644
--- a/crates/shirabe/src/downloader/file_downloader.rs
+++ b/crates/shirabe/src/downloader/file_downloader.rs
@@ -241,7 +241,10 @@ impl DownloaderInterface for FileDownloader {
                         &format!(
                             "  - Loading <info>{}</info> (<comment>{}</comment>) from cache",
                             package.get_name(),
-                            package.get_full_pretty_version(true, 0)
+                            package.get_full_pretty_version(
+                                true,
+                                crate::package::DisplayMode::SourceRefIfDev
+                            )
                         ),
                         true,
                         io_interface::VERY_VERBOSE,
@@ -263,7 +266,10 @@ impl DownloaderInterface for FileDownloader {
                     self.io.write_error(&format!(
                         "  - Downloading <info>{}</info> (<comment>{}</comment>)",
                         package.get_name(),
-                        package.get_full_pretty_version(true, 0)
+                        package.get_full_pretty_version(
+                            true,
+                            crate::package::DisplayMode::SourceRefIfDev
+                        )
                     ));
                 }
 
diff --git a/crates/shirabe/src/downloader/git_downloader.rs b/crates/shirabe/src/downloader/git_downloader.rs
index 05ef096..34f89a4 100644
--- a/crates/shirabe/src/downloader/git_downloader.rs
+++ b/crates/shirabe/src/downloader/git_downloader.rs
@@ -95,10 +95,8 @@ impl GitDownloader {
                 &format!(
                     "  - Syncing <info>{}</info> (<comment>{}</comment>) into cache",
                     package.get_name(),
-                    package.get_full_pretty_version(
-                        true,
-                        <dyn PackageInterface>::DISPLAY_SOURCE_REF_IF_DEV,
-                    ),
+                    package
+                        .get_full_pretty_version(true, crate::package::DisplayMode::SourceRefIfDev),
                 ),
                 true,
                 io_interface::NORMAL,