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/infrastructure/src/subagent/mod.rs

@@ -0,0 +1,12 @@
+//! Subagent spawning and execution engine — spawn managed sub-processes
+//! for test generation, architecture review, security review, etc.
+
+pub mod context;
+pub mod division;
+pub mod engine;
+pub mod event;
+pub mod gating;
+pub mod provider;
+pub mod spawn;
+pub mod tools;
+pub mod workspace;