feat(hooks): add ultrawork-model-override hook for per-agent model swap

src/hooks/index.ts

@@ -46,3 +46,5 @@ export { createPreemptiveCompactionHook } from "./preemptive-compaction";
 export { createTasksTodowriteDisablerHook } from "./tasks-todowrite-disabler";
 export { createWriteExistingFileGuardHook } from "./write-existing-file-guard";
 export { createHashlineReadEnhancerHook } from "./hashline-read-enhancer";
+
+export { createUltraworkModelOverrideHook } from "./ultrawork-model-override";