feat(ui): NPU package download API + npu://download events (T3.4)

src/lib/api.ts

@@ -37,6 +37,8 @@ export interface HardwareStatus {
   active: BackendId;
   modelSize: string;
   estRtf: number;
+  /** NPU package state (T3.4): chip detected, runtime staged, model fetched. */
+  npu?: { present: boolean; runtimeReady: boolean; modelInstalled: boolean };
 }
 
 export interface LlmStatus {
@@ -298,6 +300,7 @@ export const api = {
   hardwareStatus: () => invoke<HardwareStatus>("hardware_status"),
   setPreferredBackend: (backend: BackendId | "auto") =>
     invoke<void>("set_preferred_backend", { args: { backend } }),
+  downloadNpuPackage: () => invoke<void>("download_npu_package"),
   listModels: () => invoke<ModelInfo[]>("list_models"),
   downloadModel: (id: string, kind: "whisper" = "whisper") =>
     invoke<void>("download_model", { args: { kind, id } }),
@@ -440,6 +443,16 @@ export const events = {
   onHardwareChanged: (
     cb: (p: { active: BackendId; reason: string }) => void,
   ): Promise<UnlistenFn> => listen("hardware://changed", (e) => cb(e.payload as never)),
+  onNpuDownload: (
+    cb: (p: {
+      stage: "model" | "runtime" | "done";
+      file?: number;
+      received?: number;
+      total?: number | null;
+      copied?: number;
+      ready?: boolean;
+    }) => void,
+  ): Promise<UnlistenFn> => listen("npu://download", (e) => cb(e.payload as never)),
   onSyncJob: (
     cb: (p: {
       jobId: string;