feat(lexical): support local image data URLs

Allow the image insertion dialog to select a local image and embed it as a Base64 data URL, while retaining URL-based insertion and leaving video URL-only.

Extract shared abortable FileReader handling for clipboard uploads and dialog selection; add English and Simplified Chinese messages plus an interaction test covering file selection through insertion.

packages/lexical/src/actions/clipboard-images.tsx

@@ -19,6 +19,7 @@ import {
   deleteImageUploadState,
   setImageUploadState,
 } from "../image-upload-store"
+import { readFileAsDataUrl } from "../file-utils"
 import {
   $createLexicalMediaNode,
   $isLexicalMediaNode,
@@ -65,70 +66,6 @@ function isClipboardEvent(
   return "clipboardData" in event && event.clipboardData != null
 }
 
-function readFileAsDataUrl(
-  file: File,
-  signal: AbortSignal,
-  reportProgress: (progress: number) => void
-) {
-  return new Promise<string>((resolve, reject) => {
-    const reader = new FileReader()
-
-    const handleSignalAbort = () => reader.abort()
-    const cleanUp = () => signal.removeEventListener("abort", handleSignalAbort)
-
-    if (signal.aborted) {
-      reject(new DOMException("The image read was aborted.", "AbortError"))
-      return
-    }
-
-    signal.addEventListener("abort", handleSignalAbort, { once: true })
-    reader.addEventListener(
-      "error",
-      () => {
-        const error =
-          reader.error ?? new Error(`Unable to read "${file.name}".`)
-        cleanUp()
-        reject(error)
-      },
-      { once: true }
-    )
-    reader.addEventListener(
-      "abort",
-      () => {
-        cleanUp()
-        reject(new DOMException("The image read was aborted.", "AbortError"))
-      },
-      { once: true }
-    )
-    reader.addEventListener("progress", (event) => {
-      if (event.lengthComputable && event.total > 0) {
-        reportProgress(event.loaded / event.total)
-      }
-    })
-    reader.addEventListener(
-      "load",
-      () => {
-        const result = reader.result
-        cleanUp()
-
-        if (typeof result === "string") {
-          resolve(result)
-        } else {
-          reject(new Error(`Unable to read "${file.name}" as a data URL.`))
-        }
-      },
-      { once: true }
-    )
-
-    try {
-      reader.readAsDataURL(file)
-    } catch (error) {
-      cleanUp()
-      reject(error)
-    }
-  })
-}
-
 async function resolveDefaultImage(
   file: File,
   signal: AbortSignal,
@@ -143,7 +80,7 @@ async function resolveDefaultImage(
 
   return {
     alt: file.name,
-    src: await readFileAsDataUrl(file, signal, reportProgress),
+    src: await readFileAsDataUrl(file, { onProgress: reportProgress, signal }),
   }
 }