feat: make og images an emitter to properly await image generation (#1826)

* checkpoint

* make emitters async generators

* fix

* custom font spec

* replace spinner, use disk cache for fonts

* use readline instead

* make og images look nice

quartz/plugins/emitters/assets.ts

@@ -33,10 +33,9 @@ export const Assets: QuartzEmitterPlugin = () => {
 
       return graph
     },
-    async emit({ argv, cfg }, _content, _resources): Promise<FilePath[]> {
+    async *emit({ argv, cfg }, _content, _resources) {
       const assetsPath = argv.output
       const fps = await filesToCopy(argv, cfg)
-      const res: FilePath[] = []
       for (const fp of fps) {
         const ext = path.extname(fp)
         const src = joinSegments(argv.directory, fp) as FilePath
@@ -46,10 +45,8 @@ export const Assets: QuartzEmitterPlugin = () => {
         const dir = path.dirname(dest) as FilePath
         await fs.promises.mkdir(dir, { recursive: true }) // ensure dir exists
         await fs.promises.copyFile(src, dest)
-        res.push(dest)
+        yield dest
       }
-
-      return res
     },
   }
 }