feat: WASM web app (browser LesS/KEY) backed by the hel core

Run the real hel core in the browser via WebAssembly, replacing the plain-JS
ooke.github.io/sk reimplementation so the web and the CLI share one generator.

- hel core: new storage module (native fs / wasm localStorage) backs
  init/source/dump/correct; the pipe and pb branches are gated out of wasm;
  the wasm editor is completed (EditorRef) and its password prompt no longer
  blocks the single JS thread (synchronous hel_get_password instead of a
  thread::sleep poll).
- helwasm: hel_load_script for bulk import, a panic hook in hel_init, dropped
  the ok_add / web-sys leftovers; build.sh runs wasm-bindgen into a committed
  pkg/ so GitHub Pages can serve the static dir with no CI.
- UI: rewritten index.html + style.css in the kaizenkodo.org style — responsive,
  masked-but-copyable passwords with click-to-reveal, a quick-generate card plus
  a full command console, localStorage persistence, and paste import/export.

hel/src/structs.rs

@@ -392,7 +392,7 @@ pub fn init() -> Option<LKRead> {
     let lk = Arc::new(ReentrantMutex::new(RefCell::new(LK::new())));
     let editor = Editor::new();
 
-    match std::fs::read_to_string(INIT_FILE.to_str().unwrap()) {
+    match crate::storage::read(INIT_FILE.to_str().unwrap()) {
         Ok(script) => match command_parser::script(&script) {
             Ok(cmd_list) => {
                 for cmd in cmd_list {