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, 15 insertions, 4 deletions

diff --git a/crates/mozart-vcs/src/downloader/svn.rs b/crates/mozart-vcs/src/downloader/svn.rs
index 5222b06..533e15a 100644
--- a/crates/mozart-vcs/src/downloader/svn.rs
+++ b/crates/mozart-vcs/src/downloader/svn.rs
@@ -1,11 +1,17 @@
 use std::path::Path;
+use std::sync::LazyLock;
 
 use anyhow::Result;
+use regex::Regex;
 
 use crate::util::svn::SvnUtil;
 
 use super::VcsDownloader;
 
+/// Match any non-`X` status line (mirror of Composer's
+/// `{^ *[^X ] +}m`). Ignores externals (`X` prefix).
+static SVN_STATUS_RE: LazyLock<Regex> = LazyLock::new(|| Regex::new(r"(?m)^ *[^X ] +").unwrap());
+
 /// SVN downloader using checkout/switch.
 pub struct SvnDownloader {
     svn_util: SvnUtil,
@@ -46,11 +52,16 @@ impl VcsDownloader for SvnDownloader {
     }
 
     fn local_changes(&self, target: &Path) -> Result<Option<String>> {
-        let output = self.svn_util.execute(&["status"], Some(target))?;
-        if output.stdout.trim().is_empty() {
-            Ok(None)
-        } else {
+        if !target.join(".svn").is_dir() {
+            return Ok(None);
+        }
+        let output = self
+            .svn_util
+            .execute(&["status", "--ignore-externals"], Some(target))?;
+        if SVN_STATUS_RE.is_match(&output.stdout) {
             Ok(Some(output.stdout))
+        } else {
+            Ok(None)
         }
     }