fix(release): 保留空目录到 ZIP 产物

移除 count_files 和 dir_has_included_files 两个预检函数，不再在打包时
过滤空目录。所有遍历到的子目录（包括空目录和仅含 .gitkeep 的目录）
现在都会写入 ZIP 条目，确保项目目录结构完整保留。

新增三个测试覆盖：空子目录、仅 .gitkeep 目录、emod-package 匹配的
空目录。

src/commands/release.rs

@@ -214,10 +214,6 @@ fn add_directory_to_zip(
         )));
     }
 
-    if count_files(src_dir, project_dir, ignore)? == 0 {
-        return Ok(());
-    }
-
     let options = SimpleFileOptions::default();
     let mut buffer = Vec::new();
 
@@ -243,9 +239,7 @@ fn add_directory_to_zip(
             f.read_to_end(&mut buffer)?;
             zip.write_all(&buffer)?;
             buffer.clear();
-        } else if !relative_path.as_os_str().is_empty()
-            && count_files(path, project_dir, ignore)? > 0
-        {
+        } else if !relative_path.as_os_str().is_empty() {
             zip.add_directory(&path_str, options)?;
         }
     }
@@ -329,7 +323,7 @@ fn add_with_package(
             if !is_dir {
                 continue;
             }
-            // 当前目录未命中且无被包含的子孙时，无需写出目录条目。
+            // 当前目录未命中，不写出目录条目；WalkDir 仍会继续遍历子孙。
             continue;
         }
 
@@ -343,9 +337,7 @@ fn add_with_package(
                 .map_err(|e| file::io_error("读取打包文件", path, e))?;
             zip.write_all(&buffer)?;
             buffer.clear();
-        } else if !relative_path.as_os_str().is_empty()
-            && dir_has_included_files(path, project_dir, package, ignore)?
-        {
+        } else if !relative_path.as_os_str().is_empty() {
             zip.add_directory(&path_str, options)?;
         }
     }
@@ -353,57 +345,6 @@ fn add_with_package(
     Ok(())
 }
 
-fn dir_has_included_files(
-    dir: &Path,
-    project_dir: &Path,
-    package: &EmodPackage,
-    ignore: &EmodIgnore,
-) -> Result<bool> {
-    for entry in walkdir::WalkDir::new(dir) {
-        let entry = entry?;
-        let path = entry.path();
-        if !path.is_file() {
-            continue;
-        }
-        if path.display().to_string().ends_with(".gitkeep") {
-            continue;
-        }
-        let relative_path = path
-            .strip_prefix(project_dir)
-            .map_err(|e| crate::error::CliError::InvalidData(e.to_string()))?;
-        if ignore.is_ignored(relative_path, false) {
-            continue;
-        }
-        if !package.matches(relative_path, false) {
-            continue;
-        }
-        return Ok(true);
-    }
-    Ok(false)
-}
-
-fn count_files(dir: &Path, project_dir: &Path, ignore: &EmodIgnore) -> Result<usize> {
-    let mut count = 0;
-    for entry in walkdir::WalkDir::new(dir) {
-        let entry = entry?;
-        let path = entry.path();
-        if !path.is_file() {
-            continue;
-        }
-
-        let relative_path = path
-            .strip_prefix(project_dir)
-            .map_err(|e| crate::error::CliError::InvalidData(e.to_string()))?;
-
-        if !path.display().to_string().ends_with(".gitkeep")
-            && !ignore.is_ignored(relative_path, false)
-        {
-            count += 1;
-        }
-    }
-    Ok(count)
-}
-
 struct EmodIgnore {
     rules: Vec<IgnoreRule>,
 }
@@ -803,6 +744,68 @@ mod tests {
         fs::remove_dir_all(project_dir).unwrap();
     }
 
+    #[test]
+    fn package_project_keeps_empty_subdirectory() {
+        let project_dir = temp_project_dir();
+        let release_info = release_info();
+
+        fs::create_dir_all(project_dir.join("behavior_pack_abcdefgh/empty_dir")).unwrap();
+        fs::create_dir_all(project_dir.join("resource_pack_ijklmnop")).unwrap();
+
+        let pack_dirs = pack_dirs(&project_dir, &release_info);
+        let zip_path =
+            package_project_with_artifacts_env_unset(&project_dir, &pack_dirs, "1.0.0").unwrap();
+        let entries = zip_entries(&zip_path);
+
+        assert!(entries.contains(&"behavior_pack_abcdefgh/empty_dir/".to_string()));
+
+        fs::remove_dir_all(project_dir).unwrap();
+    }
+
+    #[test]
+    fn package_project_keeps_dir_with_only_gitkeep() {
+        let project_dir = temp_project_dir();
+        let release_info = release_info();
+
+        write_file(
+            &project_dir.join("behavior_pack_abcdefgh/only_gitkeep/.gitkeep"),
+            "",
+        );
+        fs::create_dir_all(project_dir.join("resource_pack_ijklmnop")).unwrap();
+
+        let pack_dirs = pack_dirs(&project_dir, &release_info);
+        let zip_path =
+            package_project_with_artifacts_env_unset(&project_dir, &pack_dirs, "1.0.0").unwrap();
+        let entries = zip_entries(&zip_path);
+
+        assert!(entries.contains(&"behavior_pack_abcdefgh/only_gitkeep/".to_string()));
+        assert!(!entries.contains(&"behavior_pack_abcdefgh/only_gitkeep/.gitkeep".to_string()));
+
+        fs::remove_dir_all(project_dir).unwrap();
+    }
+
+    #[test]
+    fn emod_package_keeps_matched_empty_subdirectory() {
+        let project_dir = temp_project_dir();
+        let release_info = release_info();
+
+        write_file(
+            &project_dir.join(".emod-package"),
+            "behavior_pack_abcdefgh/empty_dir/\n",
+        );
+        fs::create_dir_all(project_dir.join("behavior_pack_abcdefgh/empty_dir")).unwrap();
+        fs::create_dir_all(project_dir.join("resource_pack_ijklmnop")).unwrap();
+
+        let pack_dirs = pack_dirs(&project_dir, &release_info);
+        let zip_path =
+            package_project_with_artifacts_env_unset(&project_dir, &pack_dirs, "1.0.0").unwrap();
+        let entries = zip_entries(&zip_path);
+
+        assert!(entries.contains(&"behavior_pack_abcdefgh/empty_dir/".to_string()));
+
+        fs::remove_dir_all(project_dir).unwrap();
+    }
+
     #[test]
     fn package_project_includes_world_pack_json_in_default_mode() {
         let project_dir = temp_project_dir();