fix: handle root-level skill repos during installation

When a repo itself is a single skill (SKILL.md at repo root), the
discovery phase sets directory to the repo name, but after ZIP
extraction (which strips the root folder), no matching subdirectory
exists. Add a fallback to check if SKILL.md exists directly in the
extracted temp directory before reporting SKILL_DIR_NOT_FOUND.

Fixes installation of repos like zlbigger/Google-SEOs.skill.

src-tauri/src/services/skill.rs

@@ -680,6 +680,13 @@ impl SkillService {
                         found.display()
                     );
                     source = found;
+                } else if temp_dir.join("SKILL.md").exists() {
+                    // 根级 Skill：仓库本身就是 skill，SKILL.md 直接在解压根目录
+                    log::info!(
+                        "Skill directory '{}' not found, but SKILL.md exists at root, using temp_dir",
+                        target_name,
+                    );
+                    source = temp_dir.clone();
                 } else {
                     let _ = fs::remove_dir_all(&temp_dir);
                     return Err(anyhow!(format_skill_error(