feat: add escrow contract test for concurrent initialize attempts (re-entrancy guard)

[Dami24-hub]

Summary

The escrow contract guards against double-initialization with AlreadyInitialized. However, there is no test that verifies this guard works correctly when initialize() is called twice in quick succession, simulating a race condition in a test environment.

File

contracts/escrow/src/test.rs

Expected fix

Add a test:

#[test]
#[should_panic(expected = "AlreadyInitialized")]
fn test_double_initialize_panics() {
    // ... setup ...
    client.initialize(&depositor, &recipient, &arbiter, &token, &amount, &expiry);
    client.initialize(&depositor, &recipient, &arbiter, &token, &amount, &expiry); // should panic
}

Acceptance criteria

• Test exists and passes with cargo test
• Guard is verified to fire on second call