test(ui-lab): add tagger readiness scenarios

Add UI Lab scenarios for uninstalled WD and JoyTag tagger states so the lightbox and AI Workspace readiness flows can be exercised directly.

Make the Settings title-bar button accessible by label to support reliable UI Lab automation.

src/dev/mockBackend.ts

@@ -1,5 +1,15 @@
 import { emit } from "@tauri-apps/api/event";
-import type { Album, ExploreTagEntry, Folder, ImageRecord, ImageTag, SortOrder } from "../store";
+import type {
+  Album,
+  ExploreTagEntry,
+  Folder,
+  ImageRecord,
+  ImageTag,
+  SortOrder,
+  TaggerModel,
+  TaggerModelStatus,
+  TaggerRuntimeProbe,
+} from "../store";
 import { compareImages, createMockDb, mockExif } from "./mockFixtures";
 import { getMockScenario } from "./mockScenarios";
 
@@ -7,6 +17,8 @@ const db = createMockDb(getMockScenario());
 let nextFolderId = 100;
 let nextAlbumId = 100;
 let nextTagId = 10_000;
+let mockTaggerModel: TaggerModel = db.scenario === "joytag-unready" ? "joytag" : "wd";
+let mockTaggerReady = db.scenario !== "unready" && db.scenario !== "joytag-unready";
 
 type AnyPayload = Record<string, any> | undefined;
 type Rgb = [number, number, number];
@@ -55,6 +67,42 @@ function page<T>(items: T[], offset = 0, limit = 200) {
   };
 }
 
+function mockTaggerStatus(): TaggerModelStatus {
+  const modelInfo =
+    mockTaggerModel === "joytag"
+      ? {
+          model_id: "fancyfeast/joytag",
+          model_name: "JoyTag",
+          local_dir: "mock://models/joytag",
+          label_file: "top_tags.txt",
+        }
+      : {
+          model_id: "SmilingWolf/wd-swinv2-tagger-v3",
+          model_name: "wd-swinv2-tagger-v3",
+          local_dir: "mock://models/wd-swinv2-tagger-v3",
+          label_file: "selected_tags.csv",
+        };
+
+  return {
+    model_id: modelInfo.model_id,
+    model_name: modelInfo.model_name,
+    local_dir: modelInfo.local_dir,
+    ready: mockTaggerReady,
+    missing_files: mockTaggerReady ? [] : ["model.onnx", modelInfo.label_file],
+  };
+}
+
+function mockTaggerRuntimeProbe(): TaggerRuntimeProbe {
+  if (!mockTaggerReady) {
+    throw new Error(`${mockTaggerStatus().model_name} is missing required model files`);
+  }
+  return {
+    ready: true,
+    acceleration: "auto",
+    session: { file: "model.onnx", inputs: ["input"], outputs: ["tags"] },
+  };
+}
+
 function filterImages(input: ImageRecord[], payload: unknown): ImageRecord[] {
   const p = params(payload);
   const query = String(p.search ?? p.query ?? "").trim().toLowerCase();
@@ -463,10 +511,19 @@ export async function handleMockCommand(cmd: string, payload?: unknown): Promise
       return reset;
     }
     case "get_tagger_model_status":
-      return { model_id: "SmilingWolf/wd-vit-tagger-v3", model_name: "WD ViT Tagger", local_dir: "mock://models/tagger", ready: true, missing_files: [] };
+      return mockTaggerStatus();
     case "get_tagger_model":
+      return mockTaggerModel;
     case "set_tagger_model":
-      return p.model ?? "wd";
+      mockTaggerModel = p.model ?? "wd";
+      mockTaggerReady = db.scenario !== "unready" && db.scenario !== "joytag-unready";
+      return mockTaggerModel;
+    case "prepare_tagger_model":
+      mockTaggerReady = true;
+      return mockTaggerStatus();
+    case "delete_tagger_model":
+      mockTaggerReady = false;
+      return mockTaggerStatus();
     case "get_tagger_acceleration":
     case "set_tagger_acceleration":
       return p.acceleration ?? "auto";
@@ -477,7 +534,7 @@ export async function handleMockCommand(cmd: string, payload?: unknown): Promise
     case "set_tagger_batch_size":
       return p.batch_size ?? 8;
     case "probe_tagger_runtime":
-      return { ready: true, acceleration: "auto", session: { file: "model.onnx", inputs: ["input"], outputs: ["tags"] } };
+      return mockTaggerRuntimeProbe();
     case "get_tagging_queue_scope":
       return "all";
     case "get_tagging_queue_folder_ids":