fix(ai-tags): refresh tagger readiness for lightbox

Load the selected tagger model and model status during app startup so the lightbox AI tags action does not stay disabled until Settings refreshes the state.

Refresh readiness after tagger downloads complete and replace stale WD-specific unavailable copy with generic AI tagger wording.

src-tauri/src/tagger.rs

@@ -466,7 +466,8 @@ pub fn probe_tagger_runtime(app_data_dir: &Path) -> Result<TaggerRuntimeProbe> {
     let status = tagger_model_status(app_data_dir);
     if !status.ready {
         anyhow::bail!(
-            "WD Tagger model is missing {} required file(s): {}",
+            "{} is missing {} required file(s): {}",
+            status.model_name,
             status.missing_files.len(),
             status.missing_files.join(", ")
         );