feat: Refactor kvstore and vault to use features and logging

- Remove hardcoded dependencies in kvstore Cargo.toml; use features
  instead. This allows for more flexible compilation for different
  targets (native vs. WASM).
- Improve logging in vault crate using the `log` crate. This makes
  debugging easier and provides more informative output during
  execution.  Native tests use `env_logger`, WASM tests use
  `console_log`.
- Update README to reflect new logging best practices.
- Add cfg attributes to native and wasm modules to improve clarity.
- Update traits.rs to specify Send + Sync behavior expectations.

kvstore/src/native.rs

@@ -2,6 +2,7 @@
 //!
 //! # Runtime Requirement
 //!
+#![cfg(not(target_arch = "wasm32"))]
 //! **A Tokio runtime must be running to use this backend.**
 //! This library does not start or manage a runtime; it assumes that all async methods are called from within an existing Tokio runtime context (e.g., via `#[tokio::main]` or `tokio::test`).
 //!
@@ -10,11 +11,18 @@
 //! # Example
 //!
 
-use crate::traits::KVStore;
-use crate::error::{KVError, Result};
+//! Native backend for kvstore using sled
+//! Only compiled for non-wasm32 targets
 
+#[cfg(not(target_arch = "wasm32"))]
+use crate::traits::KVStore;
+#[cfg(not(target_arch = "wasm32"))]
+use crate::error::{KVError, Result};
+#[cfg(not(target_arch = "wasm32"))]
 use async_trait::async_trait;
+#[cfg(not(target_arch = "wasm32"))]
 use sled::Db;
+#[cfg(not(target_arch = "wasm32"))]
 use std::sync::Arc;
 
 #[derive(Clone)]

kvstore/src/traits.rs

@@ -16,6 +16,11 @@ use crate::error::Result;
 /// - contains_key (was exists)
 /// - keys
 /// - clear
+/// Async key-value store interface for both native and WASM backends.
+///
+/// For native (non-wasm32) backends, implementers should be `Send + Sync` to support async usage.
+/// For WASM (wasm32) backends, `Send + Sync` is not required.
+#[async_trait::async_trait]
 pub trait KVStore {
     async fn get(&self, key: &str) -> Result<Option<Vec<u8>>>;
     async fn set(&self, key: &str, value: &[u8]) -> Result<()>;

kvstore/src/wasm.rs

@@ -13,12 +13,15 @@
 //!
 
 
+//! WASM backend for kvstore using IndexedDB (idb crate)
+//! Only compiled for wasm32 targets
+
+#[cfg(target_arch = "wasm32")]
 use crate::traits::KVStore;
+#[cfg(target_arch = "wasm32")]
 use crate::error::{KVError, Result};
-
+#[cfg(target_arch = "wasm32")]
 use async_trait::async_trait;
-
-
 #[cfg(target_arch = "wasm32")]
 use idb::{Database, TransactionMode, Factory};
 #[cfg(target_arch = "wasm32")]