feat(hooks): add todo-description-override hook to enforce atomic todo format

Override TodoWrite description via tool.definition hook to require
WHERE/WHY/HOW/RESULT in each todo title and enforce 1-3 tool call
granularity.

src/plugin-interface.ts

@@ -71,5 +71,9 @@ export function createPluginInterface(args: {
       ctx,
       hooks,
     }),
+
+    "tool.definition": async (input, output) => {
+      await hooks.todoDescriptionOverride?.["tool.definition"]?.(input, output)
+    },
   }
 }