Add CPU rendering toggle for video wallpapers

Add videoCpuMode setting that passes --cpu to aether-wp, skipping
GPU rendering entirely. Fixes silent failures on systems where the
automatic GPU-to-CPU fallback doesn't trigger.

Author: bjarneo

frontend/src/lib/components/sidebar/TemplateToggles.svelte

@@ -42,3 +42,42 @@
         {/each}
     </div>
 </div>
+
+<div class="mt-4">
+    <h3
+        class="text-fg-dimmed mb-2 text-[10px] font-medium uppercase tracking-wider"
+    >
+        Video Wallpaper
+    </h3>
+    <div class="flex flex-col gap-2">
+        <label class="flex cursor-pointer items-center justify-between gap-3">
+            <div>
+                <span class="text-fg-secondary text-[11px]">CPU rendering</span>
+                <p class="text-fg-dimmed text-[9px] leading-snug">
+                    Use software rendering for video wallpapers. Enable if
+                    videos fail to display.
+                </p>
+            </div>
+            <button
+                class="relative h-4 w-8 shrink-0 transition-colors duration-150
+                    {getSettings().videoCpuMode
+                    ? 'bg-accent'
+                    : 'bg-bg-surface border-border border'}"
+                onclick={() =>
+                    updateSettings({
+                        videoCpuMode: !getSettings().videoCpuMode,
+                    })}
+                role="switch"
+                aria-checked={getSettings().videoCpuMode}
+                aria-label="Toggle CPU rendering"
+            >
+                <span
+                    class="bg-fg-primary absolute left-0.5 top-0.5 h-3 w-3 transition-transform duration-150
+                        {getSettings().videoCpuMode
+                        ? 'translate-x-4'
+                        : 'translate-x-0'}"
+                ></span>
+            </button>
+        </label>
+    </div>
+</div>

frontend/src/lib/stores/settings.svelte.ts

@@ -6,6 +6,7 @@ const defaults: Settings = {
     includeVscode: false,
     includeNeovim: true,
     selectedNeovimConfig: '',
+    videoCpuMode: false,
 };
 
 let settings = $state<Settings>({...defaults});

frontend/src/lib/types/theme.ts

@@ -44,6 +44,7 @@ export interface Settings {
     includeVscode: boolean;
     includeNeovim: boolean;
     selectedNeovimConfig: string;
+    videoCpuMode: boolean;
 }
 
 export const DEFAULT_ADJUSTMENTS: Adjustments = {

internal/theme/applier.go

@@ -162,7 +162,8 @@ func stopAetherWp() {
 }
 
 // applyWallpaperAetherWp starts aether-wp for animated wallpapers.
-func applyWallpaperAetherWp(mediaPath string) error {
+// When cpuMode is true, passes --cpu to skip GPU and use software rendering.
+func applyWallpaperAetherWp(mediaPath string, cpuMode bool) error {
 	wpBin := aetherWpPath()
 	if wpBin == "" {
 		return fmt.Errorf("aether-wp binary not found")
@@ -171,10 +172,20 @@ func applyWallpaperAetherWp(mediaPath string) error {
 	_ = platform.RunAsync("pkill", "-x", "swaybg")
 	stopAetherWp()
 
-	if err := platform.RunAsync("setsid", wpBin, mediaPath); err != nil {
+	args := []string{wpBin}
+	if cpuMode {
+		args = append(args, "--cpu")
+	}
+	args = append(args, mediaPath)
+
+	if err := platform.RunAsync("setsid", args...); err != nil {
 		return fmt.Errorf("failed to start aether-wp: %w", err)
 	}
-	log.Printf("aether-wp started for: %s", mediaPath)
+	mode := "GPU"
+	if cpuMode {
+		mode = "CPU"
+	}
+	log.Printf("aether-wp started (%s) for: %s", mode, mediaPath)
 	return nil
 }
 
@@ -215,7 +226,7 @@ func ApplyWallpaper(wallpaperPath string, settings Settings) error {
 	log.Printf("Created wallpaper symlink: %s -> %s", symlinkPath, wallpaperPath)
 
 	if IsAnimatedWallpaper(wallpaperPath) && IsAetherWpAvailable() {
-		return applyWallpaperAetherWp(wallpaperPath)
+		return applyWallpaperAetherWp(wallpaperPath, settings.VideoCpuMode)
 	}
 	return applyWallpaperSwaybg(symlinkPath)
 }

internal/theme/writer.go

@@ -57,6 +57,7 @@ type Settings struct {
 	IncludeNeovim        bool            `json:"includeNeovim"`
 	SelectedNeovimConfig string          `json:"selectedNeovimConfig"`
 	ExcludedApps         map[string]bool `json:"excludedApps,omitempty"`
+	VideoCpuMode         bool            `json:"videoCpuMode"`
 }
 
 // ApplyResult is returned by ApplyTheme with the outcome of theme application.