chore: add wasm console demo

wasm_console_demo/main.js

@@ -0,0 +1,13 @@
+// Minimal loader for the vault WASM module for console interaction
+// Adjust the module path if needed (this assumes the default wasm-pack output in the parent dir)
+import init, * as vault from './wasm_app.js';
+
+window.vault = null;
+
+init().then(() => {
+    window.vault = vault;
+    console.log('Vault WASM module loaded. Use window.vault.<function>() in the console.');
+});
+
+// Optional: Helper to convert Uint8Array to hex
+window.toHex = arr => Array.from(new Uint8Array(arr)).map(b => b.toString(16).padStart(2, '0')).join('');