Add SelfFreezoneClient wrapper for Self components

- Created SelfFreezoneClient in Self components
- Wraps SDK FreezoneScriptClient for Self-specific operations
- Implements send_verification_email method
- Uses Rhai script template for email verification
- Includes template variable substitution
- Added serde-wasm-bindgen dependency

Usage:
  let client = SelfFreezoneClient::builder()
      .supervisor_url("http://localhost:8080")
      .secret("my-secret")
      .build()?;

  client.send_verification_email(
      "user@example.com",
      "123456",
      "https://verify.com/abc"
  ).await?;

server/Cargo.toml

@@ -23,3 +23,5 @@ tracing = "0.1"
 tracing-subscriber = "0.3"
 anyhow = "1.0"
 clap = { version = "4.0", features = ["derive"] }
+jsonwebtoken = "9.0"
+base64 = "0.22"