fix(git): add storage_path existence pre-check in run_sync

Fail fast if repo storage_path does not exist on disk, before
blocking the thread pool with spawn_blocking. This prevents
invalid tasks from consuming blocking threads while failing.

libs/git/hook/pool/mod.rs

@@ -259,6 +259,13 @@ impl GitHookPool {
             .map_err(crate::GitError::from)?
             .ok_or_else(|| crate::GitError::NotFound(format!("repo {} not found", repo_id)))?;
 
+        // Fail fast if storage path doesn't exist — avoid blocking spawn_blocking thread pool.
+        if !std::path::Path::new(&repo.storage_path).exists() {
+            return Err(crate::GitError::NotFound(format!(
+                "storage path does not exist: {}", repo.storage_path
+            )));
+        }
+
         let db_clone = self.db.clone();
         let cache_clone = self.cache.clone();
         let repo_clone = repo.clone();