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

.env.example

@@ -0,0 +1,23 @@
+# SMTP server
+APP_SMTP_HOST=smtp.example.com
+APP_SMTP_PORT=587
+APP_SMTP_USERNAME=
+APP_SMTP_PASSWORD=
+APP_SMTP_FROM_EMAIL=noreply@example.com
+APP_SMTP_FROM_NAME=EmailKS
+APP_SMTP_REPLY_TO=
+# one of: none | starttls | tls
+APP_SMTP_TLS=starttls
+APP_SMTP_TIMEOUT_SECS=30
+APP_SMTP_HELO_NAME=
+# Allow per-request From override (disabled by default)
+APP_SMTP_ALLOW_REQUEST_FROM=false
+
+# RPC listen address (defaults to loopback)
+APP_SMTP_LISTEN_ADDR=127.0.0.1:50051
+
+# Optional queue capacity (bounded to 1000 if unset; set 0 for unbounded)
+APP_SMTP_QUEUE_CAPACITY=
+
+# Log level (trace|debug|info|warn|error)
+RUST_LOG=info