feat: Add WASM support and browser extension infrastructure

- Add WASM build target and dependencies for all crates.
- Implement IndexedDB-based persistent storage for WASM.
- Create browser extension infrastructure (UI, scripting, etc.).
- Integrate Rhai scripting engine for secure automation.
- Implement user stories and documentation for the extension.

Cargo.toml

@@ -3,5 +3,7 @@ resolver = "2"
 members = [
     "kvstore",
     "vault",
-    "evm_client"
+    "evm_client",
+    "wasm",
 ]
+