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?;

components/scripts/email_verification.rhai

@@ -0,0 +1,62 @@
+// Email verification script template for Self
+// Variables: {{email}}, {{code}}, {{url}}
+
+print("=== Self: Sending Email Verification ===");
+print("Email: {{email}}");
+print("Code: {{code}}");
+
+// Get freezone context
+let freezone_pubkey = "04e58314c13ea3f9caed882001a5090797b12563d5f9bbd7f16efe020e060c780b446862311501e2e9653416527d2634ff8a8050ff3a085baccd7ddcb94185ff56";
+let freezone_ctx = get_context([freezone_pubkey]);
+
+// Get email client from context
+let email_client = freezone_ctx.get("email_client");
+if email_client == () {
+    print("ERROR: Email client not configured in freezone context");
+    return #{
+        success: false,
+        error: "Email client not configured"
+    };
+}
+
+// Get verification email template
+let template = freezone_ctx.get("verification_email");
+if template == () {
+    print("ERROR: Verification email template not found");
+    return #{
+        success: false,
+        error: "Email template not configured"
+    };
+}
+
+// Create verification record
+let verification = new_verification()
+    .email("{{email}}")
+    .code("{{code}}")
+    .transport("email")
+    .expires_in(86400);  // 24 hours
+
+freezone_ctx.save(verification);
+print("✓ Verification record created");
+
+// Send email using template
+let result = email_client.send_from_template(
+    template,
+    "{{email}}",
+    #{
+        url: "{{url}}",
+        code: "{{code}}"
+    }
+);
+
+print("✓ Verification email sent successfully");
+print("   To: {{email}}");
+print("   Code: {{code}}");
+
+// Return success response
+#{
+    success: true,
+    email: "{{email}}",
+    code: "{{code}}",
+    expires_in: 86400
+}