refactor(registry): plumb RepositorySet and executor through callers

ResolveRequest and LockFileGenerationRequest now take Arc<RepositorySet>
instead of a raw Cache. install_from_lock now accepts &mut dyn
InstallerExecutor instead of constructing FilesystemExecutor internally.
Both changes expose the DI injection points needed by the upcoming
in-process test harness, where Packagist must be replaced with an empty
RepositorySet (Composer's `'packagist' => false` test config) and
filesystem install execution must be replaced with a tracing recorder
(Composer's InstallationManagerMock).

The eager VCS scan and inline-package preload still happen inside
resolve(), so the RawRepository array is kept on ResolveRequest as
raw_repositories - migrating those through RepositorySet remains a
follow-up. RepositorySet gains with_packagist and empty constructors so
production callers and future tests have a uniform construction shape.

All 136 enabled installer fixtures + 114 mozart-registry tests + 541
mozart lib tests still green; clippy clean.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

1 files changed, 16 insertions, 0 deletions

diff --git a/crates/mozart-registry/src/repository/mod.rs b/crates/mozart-registry/src/repository/mod.rs
index 1ab8797..0f742a3 100644
--- a/crates/mozart-registry/src/repository/mod.rs
+++ b/crates/mozart-registry/src/repository/mod.rs
@@ -81,6 +81,22 @@ impl RepositorySet {
         Self { repos }
     }
 
+    /// Production default: a single [`packagist_repo::PackagistRepository`]
+    /// backed by the given on-disk cache. Mirrors what Composer does when
+    /// no `'packagist' => false` entry appears in the merged config.
+    pub fn with_packagist(repo_cache: crate::cache::Cache) -> Self {
+        Self::new(vec![Box::new(packagist_repo::PackagistRepository::new(
+            repo_cache,
+        ))])
+    }
+
+    /// An empty set. Mirrors Composer's `'packagist' => false` test config:
+    /// resolution proceeds entirely from packages already in the pool
+    /// (eager VCS scan, inline `type: package` repos, the locked repository).
+    pub fn empty() -> Self {
+        Self::new(Vec::new())
+    }
+
     pub fn is_empty(&self) -> bool {
         self.repos.is_empty()
     }