feat: Add basic project structure and initial crates

- Added basic project structure with workspace and crates:
  `kvstore`, `vault`, `evm_client`, `cli_app`, `web_app`.
- Created initial `Cargo.toml` files for each crate.
- Added placeholder implementations for key components.
- Included initial documentation files (`README.md`, architecture
  docs, repo structure).
- Included initial implementaion for kvstore crate(async API, backend abstraction, separation of concerns, WASM/native support, testability)
- Included native and browser tests for the kvstore crate

evm_client/Cargo.toml

@@ -0,0 +1,13 @@
+[package]
+name = "evm_client"
+version = "0.1.0"
+edition = "2021"
+
+[lib]
+path = "src/lib.rs"
+
+[dependencies]
+vault = { path = "../vault" }
+async-trait = "0.1"
+alloy = "0.6"
+thiserror = "1"