Add DATA_PATHS golden standard and resolve_data_path helpers.

Document skill-owned file layout under user data dir, extend runtime_paths with standard subdir helpers, add POLICY-DATA-PATH-001, and update CONFIG/RUNTIME cross-references.

Co-authored-by: Cursor <cursoragent@cursor.com>

.env.example

@@ -19,3 +19,12 @@ OPENCLAW_ARTIFACTS_ON_FAILURE=1        # 1=失败截图(默认)
 STEP_DELAY_MIN=1.0                     # 步骤间随机等待下限(秒)
 STEP_DELAY_MAX=5.0                     # 步骤间随机等待上限(秒)
 HUMAN_WAIT_TIMEOUT=180                 # 滑块/验证码/2FA 等人工超时(秒)
+
+# ── 数据目录子路径（见 development/DATA_PATHS.md；留空则用 skill 数据目录下默认子文件夹）──
+# 相对路径相对于 {JIANGCHANG_DATA_ROOT}/{USER_ID}/{slug}/，不是 workspace / CWD
+# SKILL_DOWNLOAD_DIR=downloads
+# SKILL_IMPORT_DIR=imports
+# SKILL_EXPORT_DIR=exports
+# SKILL_UPLOAD_DIR=uploads
+# SKILL_CACHE_DIR=cache
+# SKILL_TEMP_DIR=temp