chore(project): initialize project with core configuration and dependencies

- Add .gitignore and .env.example files for project setup
- Create build script for proto compilation with tonic-prost
- Generate Cargo.lock with all project dependencies
- Configure project structure and ignore patterns for development environment

email.rs

@@ -0,0 +1,40 @@
+use std::sync::Arc;
+
+use lettre::{AsyncSmtpTransport, AsyncTransport, Tokio1Executor};
+
+pub use crate::error::EmailError;
+use crate::{
+    config::SmtpConfig, email_build::build_message_from_parts, pb::email::v1::SendEmailRequest,
+    queue::EmailJob,
+};
+
+pub(crate) type Mailer = AsyncSmtpTransport<Tokio1Executor>;
+
+#[derive(Clone)]
+pub struct EmailSender {
+    config: Arc<SmtpConfig>,
+    mailer: Mailer,
+}
+
+impl EmailSender {
+    pub fn new(config: SmtpConfig) -> Result<Self, EmailError> {
+        let mailer = crate::email_build::build_mailer(&config)?;
+        Ok(Self {
+            config: Arc::new(config),
+            mailer,
+        })
+    }
+
+    pub async fn send(&self, request: &SendEmailRequest) -> Result<(), EmailError> {
+        let message = build_message_from_parts(&self.config, request)?;
+        self.mailer
+            .send(message)
+            .await
+            .map_err(|e| EmailError::Send(e.to_string()))?;
+        Ok(())
+    }
+
+    pub async fn send_job(&self, job: &EmailJob) -> Result<(), EmailError> {
+        self.send(&job.request).await
+    }
+}