refactor(action): 精簡 OAuth token 初始化流程

action.yml

@@ -3,14 +3,14 @@ description: 'Antigravity CLI 工具'
 author: 'Jeffery'
 inputs:
   prompt:
-    description: ''
+    description: '傳給 Antigravity CLI 的提示詞'
     required: false
     default: "請自我介紹"
   model:
-    description: ''
+    description: 'Antigravity CLI 使用的模型'
     required: true
   oauth:
-    description: ''
+    description: 'base64 編碼的 Antigravity OAuth token 檔案內容'
     required: true
 outputs:
   text:
@@ -25,9 +25,9 @@ runs:
     run: |
       curl -fsSL https://antigravity.google/cli/install.sh | bash
       echo "$HOME/.local/bin" >> "$GITHUB_PATH"
-      oauth_dir="$HOME/.gemini/antigravity-cli"
-      oauth_file="$oauth_dir/antigravity-oauth-token"
-      mkdir -p "$oauth_dir"
+
+      oauth_file="$HOME/.gemini/antigravity-cli/antigravity-oauth-token"
+      install -d -m 700 "$(dirname "$oauth_file")"
       printf '%s' "$OAUTH" | base64 -d > "$oauth_file"
       chmod 600 "$oauth_file"
     shell: bash