chore: add project scaffolding and resources

This initial commit scaffolds the project with essential docs, assets, and build configs.
It adds Android icons, design assets, and release metadata to support mobile targets.
A fastlane config and F-Droid manifest are included to streamline builds.

- Adds F-Droid configuration for automated builds
- Includes license and privacy policy documents
- Provides app icons and assets for Android and design system

plugins/src/desktop.rs

@@ -18,6 +18,7 @@ impl<R: Runtime> Wallpaper<R> {
         WallpaperState {
             image_count: 3,
             enabled: true,
+            interval_minutes: 30,
             shuffle: true,
             lock_screen_only: true,
             current_index: 0,
@@ -56,6 +57,12 @@ impl<R: Runtime> Wallpaper<R> {
     pub fn delete_image(&self, _payload: DeleteImageRequest) -> crate::Result<WallpaperState> {
         Ok(Self::demo())
     }
+    pub fn get_image_ids(&self) -> crate::Result<Vec<String>> {
+        Ok((0..Self::demo().image_count).map(|index| format!("demo-{index}")).collect())
+    }
+    pub fn delete_images(&self, _payload: DeleteImagesRequest) -> crate::Result<WallpaperState> {
+        Ok(Self::demo())
+    }
     pub fn set_image_crop(&self, payload: ImageCropRequest) -> crate::Result<GalleryImage> {
         let url = Self::demo()
             .image_urls
@@ -82,6 +89,12 @@ impl<R: Runtime> Wallpaper<R> {
         };
         Ok(state)
     }
+    pub fn set_interval(&self, payload: IntervalRequest) -> crate::Result<WallpaperState> {
+        let mut state = Self::demo();
+        state.interval_minutes = payload.minutes;
+        state.enabled = payload.minutes > 0;
+        Ok(state)
+    }
     pub fn next_wallpaper(&self) -> crate::Result<WallpaperState> {
         let mut state = Self::demo();
         state.current_index = 1;