feat: add custom CEF V8 extensions support (#17)

* feat: Register extensions in render process

- Add CefExtensions type to hold V8 extension code
- Pass extensions through BrowserProcessAppBuilder
- Register extensions in RenderProcessHandler on WebKit initialization
- Decode JSON extensions from command line switch
- Prefix extension names with "v8/" per CEF convention
- Include actual JSON in error messages for debugging

l

* feat: refactor window.cef API and register as CEF extension

* fix: remove debug print statements in render process handler

* refactor: centralize EXTENSIONS_SWITCH constant in util.rs

* fmt

* refactor: implement Default trait for CefApiHandler

* docs: add documentation for CefApiHandler and its JavaScript API functions

---------

Co-authored-by: not-elm <elmgameinfo@gmail.com>

src/lib.rs

@@ -16,12 +16,12 @@ use crate::mute::AudioMutePlugin;
 use crate::prelude::{IpcPlugin, NavigationPlugin, WebviewPlugin};
 use crate::zoom::ZoomPlugin;
 use bevy::prelude::*;
-use bevy_cef_core::prelude::CommandLineConfig;
+use bevy_cef_core::prelude::{CefExtensions, CommandLineConfig};
 use bevy_remote::RemotePlugin;
 
 pub mod prelude {
     pub use crate::{CefPlugin, RunOnMainThread, common::*, navigation::*, webview::prelude::*};
-    pub use bevy_cef_core::prelude::CommandLineConfig;
+    pub use bevy_cef_core::prelude::{CefExtensions, CommandLineConfig};
 }
 
 pub struct RunOnMainThread;
@@ -29,6 +29,7 @@ pub struct RunOnMainThread;
 #[derive(Debug, Default)]
 pub struct CefPlugin {
     pub command_line_config: CommandLineConfig,
+    pub extensions: CefExtensions,
 }
 
 impl Plugin for CefPlugin {
@@ -37,6 +38,7 @@ impl Plugin for CefPlugin {
             LocalHostPlugin,
             MessageLoopPlugin {
                 config: self.command_line_config.clone(),
+                extensions: self.extensions.clone(),
             },
             WebviewCoreComponentsPlugin,
             WebviewPlugin,