refactor(config): require explicit BZOD data directory

src/db/mod.rs

@@ -392,12 +392,11 @@ mod db_init_tests {
 
     #[test]
     fn test_db_init() {
-        let temp_dir = PathBuf::from("./temp_test_db_dir");
+        let temp_dir = std::env::temp_dir().join(format!("test_db_init_{}", uuid::Uuid::new_v4()));
         if temp_dir.exists() {
             let _ = std::fs::remove_dir_all(&temp_dir);
         }
-        let mut config = Config::load();
-        config.data_dir = temp_dir.clone();
+        let config = Config::load_with_cli(Some(&temp_dir)).unwrap();
         let db = Db::init(&config);
 
         // Cleanup

src/db/topology.rs

@@ -10,7 +10,7 @@
 //!     └── extensions/<extension>/<extension>.db
 //! ```
 //!
-//! `<data_dir>` is `Config.data_dir` (env `DATA_DIR`, default `./data`).
+//! `<data_dir>` is `Config.data_dir` (CLI `--data-dir`, env `NX9_BZOD_DATA_DIR`, or config file).
 //! It is not renamed to `database/`. Production Docker, CasaOS, and
 //! `deploy.sh` bind this physical root.