feat(onboarding): choose AI tagger model

Add WD and JoyTag selection to the Welcome Tour AI step so users can choose the model before downloading it.

Share tagger model metadata with Settings and keep the Settings close button anchored to the modal chrome.

src/taggerModels.ts

@@ -0,0 +1,16 @@
+import type { TaggerModel } from "./store";
+
+export const TAGGER_MODELS: Record<TaggerModel, { name: string; tab: string; description: string }> = {
+  wd: {
+    name: "WD SwinV2 Tagger v3",
+    tab: "WD (anime)",
+    description:
+      "Anime-focused vision model by SmilingWolf. Generates booru-style tags with configurable confidence thresholds.",
+  },
+  joytag: {
+    name: "JoyTag",
+    tab: "JoyTag (general)",
+    description:
+      "Booru-schema tagger that also handles photographic content and is strong on NSFW concepts. The explicitness rating is derived from its tags.",
+  },
+};