feat(api): implement user authentication and registration endpoints

- Add main application logic in `api/src/main.rs` to initialize server, database, and services.
- Create authentication routes in `api/src/routes/auth.rs` for login, register, logout, and user info retrieval.
- Implement configuration route in `api/src/routes/config.rs` to expose application settings.
- Define application state management in `api/src/state.rs` to share user service and configuration.
- Set up Docker Compose configuration in `compose.yml` for backend, worker, and database services.
- Establish domain logic in `domain` crate with user entities, repositories, and services.
- Implement SQLite user repository in `infra/src/user_repository.rs` for user data persistence.
- Create database migration handling in `infra/src/db.rs` and session store in `infra/src/session_store.rs`.
- Add necessary dependencies and features in `Cargo.toml` files for both `domain` and `infra` crates.

domain/src/repositories.rs

@@ -0,0 +1,28 @@
+//! Reference Repository ports (traits)
+//! 
+//! These traits define the interface for data persistence.
+
+use async_trait::async_trait;
+use uuid::Uuid;
+
+use crate::entities::User;
+use crate::errors::DomainResult;
+
+/// Repository port for User persistence
+#[async_trait]
+pub trait UserRepository: Send + Sync {
+    /// Find a user by their internal ID
+    async fn find_by_id(&self, id: Uuid) -> DomainResult<Option<User>>;
+
+    /// Find a user by their OIDC subject (used for authentication)
+    async fn find_by_subject(&self, subject: &str) -> DomainResult<Option<User>>;
+
+    /// Find a user by their email
+    async fn find_by_email(&self, email: &str) -> DomainResult<Option<User>>;
+
+    /// Save a new user or update an existing one
+    async fn save(&self, user: &User) -> DomainResult<()>;
+
+    /// Delete a user by their ID
+    async fn delete(&self, id: Uuid) -> DomainResult<()>;
+}