feat: unify webview source into WebviewSource enum with dynamic reload (#22)

Unify CefWebviewUri and InlineHtml into a single WebviewSource enum component, eliminating the dual-component inconsistency where both existed on the same entity
Add ResolvedWebviewUri internal component as a resolution layer between user-facing source and CEF
Support dynamic reload: mutating WebviewSource at runtime automatically navigates the existing browser via browsers.navigate() without recreation
Inline HTML is served via cef://localhost/__inline__/{id} with automatic cleanup on entity despawn

examples/sprite.rs

@@ -16,7 +16,7 @@ fn spawn_camera_2d(mut commands: Commands) {
 
 fn spawn_sprite_webview(mut commands: Commands, mut images: ResMut<Assets<Image>>) {
     commands.spawn((
-        CefWebviewUri::new("https://github.com/not-elm/bevy_cef"),
+        WebviewSource::new("https://github.com/not-elm/bevy_cef"),
         Pickable::default(),
         Sprite {
             image: images.add(Image::default()),