feat(tv-ui): add slideshow pattern mode and improve admin readability

lib/features/home/unsplash_background.dart

@@ -4,6 +4,7 @@ import 'dart:math';
 import 'package:flutter/material.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 
+import '../../data/local/models.dart';
 import '../../data/services/unsplash_cache_service.dart';
 import '../../providers.dart';
 
@@ -25,6 +26,7 @@ class _UnsplashBackgroundState extends ConsumerState<UnsplashBackground> {
   String? _lastKeyword;
   int? _lastRotationHours;
   bool? _lastUseUnsplash;
+  int _lastHandledRotateNonce = 0;
 
   @override
   void initState() {
@@ -106,6 +108,50 @@ class _UnsplashBackgroundState extends ConsumerState<UnsplashBackground> {
     }
   }
 
+  void _showNextImage() {
+    if (_imagePaths.length <= 1 || !mounted) return;
+    setState(() {
+      _currentIndex = (_currentIndex + 1) % _imagePaths.length;
+    });
+  }
+
+  void _showPreviousImage() {
+    if (_imagePaths.length <= 1 || !mounted) return;
+    setState(() {
+      _currentIndex = (_currentIndex - 1 + _imagePaths.length) % _imagePaths.length;
+    });
+  }
+
+  Future<void> _handleManualRotate(
+    BackgroundRotateAction action,
+    AppSettings settings,
+  ) async {
+    if (!settings.useUnsplashBackground) return;
+
+    if (_imagePaths.isEmpty) {
+      final cachedPaths = await UnsplashCacheService.instance.getCachedImagePaths(
+        settings.unsplashKeyword,
+      );
+      if (!mounted) return;
+      if (cachedPaths.isNotEmpty) {
+        _applyImagePaths(cachedPaths);
+      }
+    }
+
+    if (_imagePaths.isEmpty) return;
+    switch (action) {
+      case BackgroundRotateAction.next:
+        _showNextImage();
+        break;
+      case BackgroundRotateAction.previous:
+        _showPreviousImage();
+        break;
+      case BackgroundRotateAction.random:
+        _nextRandomImage();
+        break;
+    }
+  }
+
   void _startTimer(int hours) {
     _rotationTimer?.cancel();
     if (hours <= 0) return;
@@ -125,6 +171,7 @@ class _UnsplashBackgroundState extends ConsumerState<UnsplashBackground> {
   @override
   Widget build(BuildContext context) {
     final settings = ref.watch(settingsProvider);
+    final rotateCommand = ref.watch(backgroundRotateCommandProvider);
 
     // Watch for config changes
     if (settings.useUnsplashBackground != _lastUseUnsplash) {
@@ -146,6 +193,14 @@ class _UnsplashBackgroundState extends ConsumerState<UnsplashBackground> {
       _startTimer(settings.unsplashRotationHours);
     }
 
+    if (rotateCommand.nonce != _lastHandledRotateNonce) {
+      _lastHandledRotateNonce = rotateCommand.nonce;
+      WidgetsBinding.instance.addPostFrameCallback((_) {
+        if (!mounted) return;
+        _handleManualRotate(rotateCommand.action, settings);
+      });
+    }
+
     if (!settings.useUnsplashBackground || _imagePaths.isEmpty) {
       return const SizedBox.shrink(); // Fallback to flat background handled underneath
     }