● Remove Hermes-incompatible WASM imports from crypto module

Drop static re-export of WasmCryptoBackend from crypto/index.js
  (import.meta breaks React Native/Hermes) and replace dynamic
  import() in setCryptoBackend('wasm') with a thrown error pointing
  to direct import for Node/Bun environments.

src/crypto/index.js

@@ -42,5 +42,7 @@ export {
 } from './provider.js';
 
 // Backends (for direct access / testing)
+// Note: WasmCryptoBackend is NOT re-exported here because it uses import.meta
+// which is incompatible with React Native/Hermes. Import it directly:
+//   import { WasmCryptoBackend } from 'salvium-js/src/crypto/backend-wasm.js';
 export { JsCryptoBackend } from './backend-js.js';
-export { WasmCryptoBackend } from './backend-wasm.js';

src/crypto/provider.js

@@ -28,10 +28,15 @@ export async function setCryptoBackend(type) {
     currentBackend = new JsCryptoBackend();
     await currentBackend.init();
   } else if (type === 'wasm') {
-    // Dynamic import to avoid loading WASM unless requested
-    const { WasmCryptoBackend } = await import('./backend-wasm.js');
-    currentBackend = new WasmCryptoBackend();
-    await currentBackend.init();
+    // Dynamic import() is not supported in React Native/Hermes.
+    // In Node/Bun, import backend-wasm.js directly:
+    //   import { WasmCryptoBackend } from './backend-wasm.js';
+    //   const backend = new WasmCryptoBackend(); await backend.init();
+    throw new Error(
+      "WASM backend cannot be loaded via setCryptoBackend() — dynamic import() " +
+      "is not available in all runtimes (e.g. Hermes). In Node/Bun, import " +
+      "WasmCryptoBackend from './crypto/backend-wasm.js' directly."
+    );
   } else {
     throw new Error(`Unknown crypto backend: ${type}. Use 'js' or 'wasm'.`);
   }