feat(TagEditor): show real-time progress when writing tags

Backend:
- Emit 'library:tag_write_progress' events with current/total count
- Progress updates as each file is written

Frontend:
- Listen for progress events during direct write mode
- Save button shows "Writing X of Y..." dynamically
- Cleanup listener on completion or error

src-tauri/src/library/commands.rs

@@ -6,7 +6,7 @@ use std::path::{Path, PathBuf};
 use std::sync::atomic::{AtomicBool, Ordering};
 use std::sync::Arc;
 use serde::Deserialize;
-use tauri::State;
+use tauri::{Emitter, State};
 use tokio::sync::Mutex;
 
 use crate::discogs::DiscogsClient;
@@ -1616,6 +1616,7 @@ pub async fn library_update_album_metadata(
 
 #[tauri::command]
 pub async fn library_write_album_metadata_to_files(
+    app: tauri::AppHandle,
     request: LibraryAlbumMetadataUpdateRequest,
     state: State<'_, LibraryState>,
 ) -> Result<(), String> {
@@ -1663,7 +1664,16 @@ pub async fn library_write_album_metadata_to_files(
                 by_file.entry(track.file_path.clone()).or_insert(track);
             }
 
+            let total = by_file.len();
+            let mut current = 0usize;
+
             for (file_path, track) in by_file {
+                current += 1;
+                // Emit progress event
+                let _ = app.emit("library:tag_write_progress", serde_json::json!({
+                    "current": current,
+                    "total": total
+                }));
                 let path = Path::new(&file_path);
                 if !path.is_file() {
                     return Err("One or more audio files were not found on disk.".to_string());

src/lib/components/LocalLibraryTagEditorModal.svelte

@@ -1,6 +1,7 @@
 <script lang="ts">
   import Modal from './Modal.svelte';
   import { invoke } from '@tauri-apps/api/core';
+  import { listen, type UnlistenFn } from '@tauri-apps/api/event';
   import { ask } from '@tauri-apps/plugin-dialog';
   import { openUrl } from '@tauri-apps/plugin-opener';
   import { showToast } from '$lib/stores/toastStore';
@@ -90,6 +91,7 @@
   let albumTotalDiscs = $state(1);
   let persistence: PersistenceMode = $state('sidecar');
   let saving = $state(false);
+  let writeProgress = $state<{ current: number; total: number } | null>(null);
 
   // Remote metadata search state
   let remoteProvider: RemoteProvider = $state('musicbrainz');
@@ -345,10 +347,17 @@
     if (!payload) return;
 
     saving = true;
+    writeProgress = null;
+    let unlisten: UnlistenFn | null = null;
+
     try {
       if (persistence === 'sidecar') {
         await invoke('library_update_album_metadata', { request: payload });
       } else {
+        // Listen for progress events
+        unlisten = await listen<{ current: number; total: number }>('library:tag_write_progress', (event) => {
+          writeProgress = event.payload;
+        });
         await invoke('library_write_album_metadata_to_files', { request: payload });
       }
       showToast('Album metadata saved', 'success');
@@ -357,6 +366,8 @@
     } catch (err) {
       alert(`Failed to save metadata: ${err}`);
     } finally {
+      if (unlisten) unlisten();
+      writeProgress = null;
       saving = false;
     }
   }
@@ -571,7 +582,13 @@
         <button class="btn btn-primary" onclick={handleSave} disabled={saving}>
           {#if saving}
             <span class="spinner-inline"></span>
-            {persistence === 'direct' ? 'Writing tags...' : 'Saving...'}
+            {#if writeProgress}
+              Writing {writeProgress.current} of {writeProgress.total}...
+            {:else if persistence === 'direct'}
+              Writing tags...
+            {:else}
+              Saving...
+            {/if}
           {:else}
             Save
           {/if}