feat(tui): add usage overlay and sidebar for displaying usage statistics and tasks

feat(tui): implement status bar with connection and turn state indicators
feat(tui): create workflow panel for agent status and progress visualization
feat(web): introduce web frontend interface with static file serving
feat(ws): add WebSocket interface for real-time communication and session management

apps/application/src/lib.rs

@@ -0,0 +1,51 @@
+//! # Zesdex Application Layer
+//!
+//! Defines port traits (interfaces) and use-case implementations for the
+//! Zesdex application. This crate depends **only** on the domain crate;
+//! it has no knowledge of infrastructure or interface adapters.
+//!
+//! ## Architecture
+//!
+//! ```text
+//! apps/application/src/
+//! ├── lib.rs              — crate root, re-exports
+//! ├── ports/              — Port traits (interfaces to external services)
+//! │   ├── provider.rs     -- ProviderService (LLM chat completion)
+//! │   ├── password.rs     -- PasswordService (hash / verify)
+//! │   ├── token.rs        -- TokenService (JWT create / verify)
+//! │   └── authentication.rs -- AuthService (combined auth)
+//! ├── auth/               — Auth use-cases
+//! │   ├── oauth_service.rs   -- OAuth 2.0 PKCE flow
+//! │   └── session_service.rs -- Session CRUD lifecycle
+//! └── cms/                — CMS use-cases
+//!     ├── conversation_service.rs -- Conversation CRUD
+//!     ├── memory_service.rs       -- Long-term memory management
+//!     └── settings_service.rs     -- Settings & app-config management
+//! ```
+//!
+//! ## Key Design Principle
+//!
+//! Application services are generic over their repository/port dependencies.
+//! Concrete implementations are injected at the composition root, keeping
+//! the use-case logic independent of any specific persistence or infrastructure
+//! technology.
+
+pub mod auth;
+pub mod cms;
+pub mod ports;
+
+// Re-export port traits for ergonomic access.
+pub use ports::*;
+
+// Re-export auth use-cases.
+pub use auth::{
+    oauth_service::{OAuthFlowStore, OAuthUseCase, TokenExchanger},
+    session_service::SessionServiceImpl,
+};
+
+// Re-export CMS use-cases.
+pub use cms::{
+    conversation_service::ConversationServiceImpl,
+    memory_service::MemoryServiceImpl,
+    settings_service::SettingsServiceImpl,
+};