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/config/schema/hooks.ts

@@ -51,6 +51,7 @@ export const HookNameSchema = z.enum([
   "anthropic-effort",
   "hashline-read-enhancer",
   "read-image-resizer",
+  "todo-description-override",
 ])
 
 export type HookName = z.infer<typeof HookNameSchema>