fix(library): integrate navigation history for back/forward support

Mouse back/forward buttons now work in local library view.

Changes:
- Add 'library-album' ViewType to navigation store
- Add selectLocalAlbum(), clearLocalAlbum(), getSelectedLocalAlbumId()
- LocalLibraryView subscribes to navigation state changes
- Album clicks use selectLocalAlbum() for proper history tracking
- Back button uses navGoBack() to navigate properly
- Tab changes navigate back to 'library' when viewing album
- +page.svelte shows LocalLibraryView for both 'library' and 'library-album'

cc

src/lib/components/views/LocalLibraryView.svelte

@@ -1,7 +1,7 @@
 <script lang="ts">
   import { invoke, convertFileSrc } from '@tauri-apps/api/core';
   import { open } from '@tauri-apps/plugin-dialog';
-  import { onMount } from 'svelte';
+  import { onMount, onDestroy } from 'svelte';
   import {
     HardDrive, Music, Disc3, Mic2, FolderPlus, Trash2, RefreshCw,
     Settings, X, Play, AlertCircle, ImageDown, Upload, Search, LayoutGrid, List
@@ -9,6 +9,15 @@
   import AlbumCard from '../AlbumCard.svelte';
   import TrackRow from '../TrackRow.svelte';
   import AddToPlaylistModal from '../AddToPlaylistModal.svelte';
+  import {
+    subscribe as subscribeNav,
+    selectLocalAlbum,
+    clearLocalAlbum,
+    getSelectedLocalAlbumId,
+    goBack as navGoBack,
+    navigateTo,
+    getNavigationState
+  } from '$lib/stores/navigationStore';
 
   // Backend types matching Rust models
   interface LocalTrack {
@@ -163,12 +172,70 @@
     showPlaylistModal = true;
   }
 
+  let unsubscribeNav: (() => void) | null = null;
+
   onMount(() => {
     loadLibraryData();
     loadFolders();
     checkDiscogsCredentials();
+
+    // Subscribe to navigation changes for back/forward support
+    unsubscribeNav = subscribeNav(() => {
+      const navState = getNavigationState();
+
+      // When navigating to library-album, load the album if we have an ID
+      if (navState.activeView === 'library-album' && navState.selectedLocalAlbumId) {
+        const albumId = navState.selectedLocalAlbumId;
+        // Find album in current list or load it
+        const album = albums.find(a => a.id === albumId);
+        if (album && (!selectedAlbum || selectedAlbum.id !== albumId)) {
+          loadAlbumById(albumId);
+        }
+      }
+
+      // When navigating back to library (from library-album), clear album selection
+      if (navState.activeView === 'library' && selectedAlbum) {
+        selectedAlbum = null;
+        albumTracks = [];
+      }
+    });
+
+    // Check if we should show an album on initial load (forward navigation)
+    const initialNavState = getNavigationState();
+    if (initialNavState.activeView === 'library-album' && initialNavState.selectedLocalAlbumId) {
+      loadAlbumById(initialNavState.selectedLocalAlbumId);
+    }
   });
 
+  onDestroy(() => {
+    if (unsubscribeNav) {
+      unsubscribeNav();
+    }
+  });
+
+  async function loadAlbumById(albumId: string) {
+    try {
+      // Find album in current list
+      let album = albums.find(a => a.id === albumId);
+
+      // If not found in loaded albums, we need to fetch album list first
+      if (!album) {
+        const allAlbums = await invoke<LocalAlbum[]>('library_get_albums', { limit: 1000, offset: 0 });
+        albums = allAlbums;
+        album = allAlbums.find(a => a.id === albumId);
+      }
+
+      if (album) {
+        selectedAlbum = album;
+        albumTracks = await invoke<LocalTrack[]>('library_get_album_tracks', {
+          albumGroupKey: album.id
+        });
+      }
+    } catch (err) {
+      console.error('Failed to load album:', err);
+    }
+  }
+
   async function checkDiscogsCredentials() {
     try {
       hasDiscogsCredentials = await invoke<boolean>('discogs_has_credentials');
@@ -229,7 +296,17 @@
 
   function handleTabChange(tab: TabType) {
     activeTab = tab;
+
+    // If we're viewing an album, navigate back to library
+    const navState = getNavigationState();
+    if (navState.activeView === 'library-album') {
+      clearLocalAlbum();
+      navigateTo('library');
+    }
+
+    // Clear local state
     selectedAlbum = null;
+    albumTracks = [];
 
     if (tab === 'artists' && artists.length === 0) {
       loadArtists();
@@ -399,6 +476,9 @@
   }
 
   async function handleAlbumClick(album: LocalAlbum) {
+    // Use navigation store for proper back/forward support
+    selectLocalAlbum(album.id);
+    // Also load album data immediately for responsive UI
     selectedAlbum = album;
     try {
       albumTracks = await invoke<LocalTrack[]>('library_get_album_tracks', {
@@ -858,7 +938,7 @@
     {@const showDiscHeaders = albumSections.length > 1}
     <!-- Album Detail View -->
     <div class="album-detail">
-      <button class="back-btn" onclick={() => (selectedAlbum = null)}>
+      <button class="back-btn" onclick={() => { clearLocalAlbum(); navGoBack(); }}>
         <X size={20} />
         <span>Back to Library</span>
       </button>

src/lib/stores/navigationStore.ts

@@ -6,7 +6,7 @@
  * fetched data, but selectedPlaylistId is managed here as it's just an ID.
  */
 
-export type ViewType = 'home' | 'search' | 'library' | 'settings' | 'album' | 'artist' | 'playlist' | 'playlist-manager' | 'favorites';
+export type ViewType = 'home' | 'search' | 'library' | 'library-album' | 'settings' | 'album' | 'artist' | 'playlist' | 'playlist-manager' | 'favorites';
 
 // Navigation state
 let activeView: ViewType = 'home';
@@ -16,6 +16,9 @@ let forwardHistory: ViewType[] = [];
 // Selected playlist ID (album/artist are full data objects in +page.svelte)
 let selectedPlaylistId: number | null = null;
 
+// Selected local album ID (for library-album view)
+let selectedLocalAlbumId: string | null = null;
+
 // Listeners
 const listeners = new Set<() => void>();
 
@@ -118,6 +121,37 @@ export function getSelectedPlaylistId(): number | null {
   return selectedPlaylistId;
 }
 
+// ============ Local Album Selection ============
+
+/**
+ * Navigate to local library album detail view
+ */
+export function selectLocalAlbum(albumId: string): void {
+  const previousId = selectedLocalAlbumId;
+  selectedLocalAlbumId = albumId;
+
+  // If already on library-album view, still notify so the component reloads with new ID
+  if (activeView === 'library-album' && previousId !== albumId) {
+    notifyListeners();
+  } else {
+    navigateTo('library-album');
+  }
+}
+
+/**
+ * Clear selected local album (called when navigating back to library)
+ */
+export function clearLocalAlbum(): void {
+  selectedLocalAlbumId = null;
+}
+
+/**
+ * Get selected local album ID
+ */
+export function getSelectedLocalAlbumId(): string | null {
+  return selectedLocalAlbumId;
+}
+
 // ============ Getters ============
 
 export function getActiveView(): ViewType {
@@ -131,6 +165,7 @@ export interface NavigationState {
   viewHistory: ViewType[];
   forwardHistory: ViewType[];
   selectedPlaylistId: number | null;
+  selectedLocalAlbumId: string | null;
   canGoBack: boolean;
   canGoForward: boolean;
 }
@@ -141,6 +176,7 @@ export function getNavigationState(): NavigationState {
     viewHistory: [...viewHistory],
     forwardHistory: [...forwardHistory],
     selectedPlaylistId,
+    selectedLocalAlbumId,
     canGoBack: viewHistory.length > 1,
     canGoForward: forwardHistory.length > 0
   };

src/routes/+page.svelte

@@ -1765,7 +1765,7 @@
           onTrackGoToArtist={handleArtistClick}
           onPlaylistClick={selectPlaylist}
         />
-      {:else if activeView === 'library'}
+      {:else if activeView === 'library' || activeView === 'library-album'}
         <LocalLibraryView
           onTrackPlay={handleLocalTrackPlay}
           onTrackPlayNext={queueLocalTrackNext}