feat(tasks): wire decompose_and_store, list_subtasks_cmd, complete_subtask_cmd; add llm_engine to AppState

src-tauri/Cargo.toml

@@ -42,6 +42,7 @@ arboard = "3.6.1"
 # stores it). Must be unconditional, not Linux-only — naming a type from
 # a transitive dep requires the dep be listed here too.
 sqlx = { version = "0.8", features = ["sqlite", "runtime-tokio"] }
+uuid = { version = "1", features = ["v4"] }
 
 [target.'cfg(target_os = "linux")'.dependencies]
 webkit2gtk = "2.0"