Refactor: remove AGPL imgly dependency and migrate background removal to python backend

src/engine/renderer/puppeteerRenderer.ts

@@ -85,7 +85,6 @@ export async function renderFrames(options: RenderFrameOptions): Promise<string[
       `--window-size=${width},${height}`,
       '--no-sandbox',
       '--disable-setuid-sandbox',
-      '--disable-gpu',
       '--disable-dev-shm-usage',
     ],
   });
@@ -149,6 +148,7 @@ export async function renderFrames(options: RenderFrameOptions): Promise<string[
         type: imageFormat,
         quality: imageFormat === 'jpeg' ? quality : undefined,
         clip: { x: 0, y: 0, width, height },
+        omitBackground: imageFormat === 'png',
       });
 
       framePaths.push(framePath);