feat(og-image): add config option to use default og image for root path

quartz/components/Head.tsx

@@ -45,6 +45,7 @@ const defaultOptions: SocialImageOptions = {
   width: 1200,
   height: 630,
   imageStructure: defaultImage,
+  excludeRoot: false,
 }
 
 export default (() => {
@@ -145,6 +146,13 @@ export default (() => {
       fileData.frontmatter?.socialImage ??
       fileData.frontmatter?.image ??
       fileData.frontmatter?.cover
+
+    // Override with default og image if config option is set
+    if (fileData.slug === "index") {
+      ogImagePath = ogImageDefaultPath
+    }
+
+    // Override with frontmatter url if existing
     if (frontmatterImgUrl) {
       ogImagePath = `https://${cfg.baseUrl}/static/${frontmatterImgUrl}`
     }

quartz/util/imageHelper.ts

@@ -64,6 +64,10 @@ export type SocialImageOptions = {
    * Width to generate image with in pixels (should be around 1200px)
    */
   width: number
+  /**
+   * Wether to use the auto generated image for the root path ("/", when set to false) or the default og image (when set to true).
+   */
+  excludeRoot: boolean
   /**
    * JSX to use for generating image. See satori docs for more info (https://github.com/vercel/satori)
    * @param cfg global quartz config