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.

evm_client/tests/wasm.rs

@@ -1,3 +1,5 @@
+// This file contains WASM-only integration tests for EVM client balance and signing logic.
+// All code is strictly separated from native using cfg attributes.
 #![cfg(target_arch = "wasm32")]
 use wasm_bindgen_test::*;
 wasm_bindgen_test::wasm_bindgen_test_configure!(run_in_browser);