fix(status): align with Composer's StatusCommand pipeline

Replace the dist-hash tree-diff implementation with Composer's VCS-level
status flow: three buckets (errors / unpushed_changes / vcs_version_changes)
populated via ChangeReportInterface / DvcsDownloaderInterface /
VcsCapableDownloaderInterface, and a bitfield exit code (1|2|4) instead
of always 1.

Supporting work:
- mozart-semver: add normalize_branch (VersionParser::normalizeBranch).
- mozart-vcs: extend VcsDownloader trait with unpushed_changes /
  vcs_reference; port GitDownloader::getUnpushedChanges (HEAD-ref
  discovery + git diff --name-status remote...branch + two-pass fetch);
  fix git status invocation to use --untracked-files=no (Composer parity);
  add hasMetadataRepository preconditions to git/hg/svn local_changes;
  port VersionGuesser (git/hg/svn dispatch — Fossil omitted, feature
  branch detection runs sequentially instead of via async promises).
- mozart-core: extend LocalPackage with pretty_version, package_type,
  installation_source, source, dist, extra; add InstallationSource and
  PackageReference. factory.rs reads them from installed.json.
- mozart-registry: new download_manager mirroring
  DownloadManager::getDownloaderForPackage.

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

1 files changed, 16 insertions, 0 deletions

diff --git a/crates/mozart-vcs/src/downloader/mod.rs b/crates/mozart-vcs/src/downloader/mod.rs
index 7186348..8948921 100644
--- a/crates/mozart-vcs/src/downloader/mod.rs
+++ b/crates/mozart-vcs/src/downloader/mod.rs
@@ -24,8 +24,24 @@ pub trait VcsDownloader {
 
     /// Detect local changes in the working copy.
     /// Returns `None` if clean, `Some(diff)` if modified.
+    /// Mirrors `Composer\Downloader\ChangeReportInterface::getLocalChanges`.
     fn local_changes(&self, target: &Path) -> Result<Option<String>>;
 
+    /// Detect commits present locally but not on the tracking remote.
+    /// Returns `None` if there are no unpushed commits or the concept does
+    /// not apply (only `GitDownloader` implements this in Composer's
+    /// `DvcsDownloaderInterface`).
+    fn unpushed_changes(&self, _target: &Path) -> Result<Option<String>> {
+        Ok(None)
+    }
+
+    /// Resolve the working copy's current VCS reference (e.g. commit hash).
+    /// Returns `None` if no reference can be determined. Mirrors
+    /// `Composer\Downloader\VcsCapableDownloaderInterface::getVcsReference`.
+    fn vcs_reference(&self, _target: &Path) -> Result<Option<String>> {
+        Ok(None)
+    }
+
     /// Get commit log between two references.
     fn commit_logs(&self, from: &str, to: &str, target: &Path) -> Result<String>;
 }