refactor(notif): Use discord_client crate

- Moved code into a new Rust crate `node-notifier`
- Create new crate discord client
- node_notifier use now discord client

discord_client/Cargo.toml

@@ -0,0 +1,12 @@
+[package]
+name = "discord_client"
+version = "0.1.0"
+edition = "2024"
+
+[dependencies]
+reqwest = { version = "0.12.22", features = ["blocking", "json"] }
+serde = "1.0.219"
+serde_json = "1.0.140"
+
+[dev-dependencies]
+mockito = "1.7.0"

discord_client/src/lib.rs

@@ -0,0 +1,68 @@
+pub struct DiscordNotifier {
+    webhook_url: String,
+    username: String,
+    avatar_url: String,
+}
+
+impl DiscordNotifier {
+    pub fn new(webhook_url: String, username: String, avatar_url: String) -> DiscordNotifier {
+        DiscordNotifier {
+            webhook_url,
+            username,
+            avatar_url,
+        }
+    }
+
+    pub fn send_notification(&self, message: &str) -> Result<(), Box<dyn std::error::Error>> {
+        let client = reqwest::blocking::Client::new();
+        let payload = serde_json::json!({
+            "content": message,
+            "username": self.username,
+            "avatar_url": self.avatar_url
+        });
+
+        client
+            .post(&self.webhook_url)
+            .json(&payload)
+            .send()
+            .map(|_| ())
+            .map_err(|e| Box::new(e) as Box<dyn std::error::Error>)
+    }
+}
+
+#[test]
+fn test_send_notification() {
+    use serde_json::json;
+
+    const USERNAME: &str = "TEST_USER";
+    const AVATAR_URL: &str = "https://example.com/avatar.png";
+    const MESSAGE: &str = "Test message";
+
+    let mut server = mockito::Server::new();
+
+    let mock = server
+        .mock("POST", "/")
+        .with_status(204)
+        .match_header("content-type", "application/json")
+        .match_body(mockito::Matcher::Json(json!({
+            "content": MESSAGE,
+            "username": USERNAME,
+            "avatar_url": AVATAR_URL
+        })))
+        .create();
+
+    let webhook_url = server.url();
+
+    let notifier = DiscordNotifier::new(
+        webhook_url.clone(),
+        USERNAME.to_string(),
+        AVATAR_URL.to_string(),
+    );
+    let result = notifier.send_notification(MESSAGE);
+    assert!(
+        result.is_ok(),
+        "{}",
+        format!("Failed to send notification: {:?}", result.err())
+    );
+    mock.assert();
+}