feat(vcs): wire cache-vcs-dir setting through to drivers

DriverConfig used to expose a generic cache_dir hardcoded to a
relative ".cache/mozart/vcs", with each driver appending its own
"git"/"hg" subdir. As a result, the cache-vcs-dir setting (and
COMPOSER_CACHE_VCS_DIR env var) had no effect on where mirrors
were actually stored.

Replace cache_dir with cache_vcs_dir, resolving its default the
same way Composer does (COMPOSER_CACHE_VCS_DIR → COMPOSER_CACHE_DIR/vcs
→ XDG/HOME fallbacks), and have GitDriver/HgDriver use it directly.
This brings the Mozart cache layout in line with Composer's: a single
shared vcs root with one subdirectory per sanitized URL.

1 files changed, 2 insertions, 2 deletions

diff --git a/crates/mozart-vcs/src/driver/hg.rs b/crates/mozart-vcs/src/driver/hg.rs
index 0782775..f476e6a 100644
--- a/crates/mozart-vcs/src/driver/hg.rs
+++ b/crates/mozart-vcs/src/driver/hg.rs
@@ -51,8 +51,8 @@ impl HgDriver {
 
 impl VcsDriver for HgDriver {
     async fn initialize(&mut self) -> Result<()> {
-        let cache_dir = self.config.cache_dir.join("hg");
-        std::fs::create_dir_all(&cache_dir)?;
+        let cache_dir = &self.config.cache_vcs_dir;
+        std::fs::create_dir_all(cache_dir)?;
         let repo_dir = cache_dir.join(crate::util::git::GitUtil::sanitize_url(&self.url));
 
         if repo_dir.join(".hg").is_dir() {