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/locales/en.ts

@@ -68,18 +68,29 @@ export const messages = {
   "lexical.media.alignLeft": "Align image left",
   "lexical.media.alignRight": "Align image right",
   "lexical.media.caption": "Caption",
+  "lexical.media.chooseImageFile": "Choose image",
   "lexical.media.controls": "Image controls",
   "lexical.media.deleteImage": "Delete image",
   "lexical.media.editCaption": "Edit caption",
   "lexical.media.imageAlt": "Alternative text",
-  "lexical.media.imageAltDescription": "Leave blank for decorative images; provide it when the image conveys information.",
-  "lexical.media.imageDescription": "Enter a publicly accessible image URL and provide alternative text.",
+  "lexical.media.imageAltDescription":
+    "Leave blank for decorative images; provide it when the image conveys information.",
+  "lexical.media.imageDescription":
+    "Enter an image URL or choose a local image file, then provide alternative text.",
+  "lexical.media.imageFile": "Image file",
+  "lexical.media.imageFileDescription":
+    "Choose an image from your device to embed it as a Base64 data URL.",
+  "lexical.media.imageFileReadError":
+    "The image could not be read. Try selecting it again.",
   "lexical.media.imageUrl": "Image URL",
+  "lexical.media.readingImageFile": "Reading image…",
   "lexical.media.uploading": "Uploading image",
   "lexical.media.uploadingProgress": "Uploading {progress}%",
   "lexical.media.uploadProgress": "Image upload progress",
-  "lexical.media.urlDescription": "Supports absolute URLs and relative URLs within this site.",
-  "lexical.media.videoDescription": "Enter a publicly accessible video URL in a browser-supported format.",
+  "lexical.media.urlDescription":
+    "Supports absolute URLs and relative URLs within this site.",
+  "lexical.media.videoDescription":
+    "Enter a publicly accessible video URL in a browser-supported format.",
   "lexical.media.videoPoster": "Video poster URL",
   "lexical.media.videoUrl": "Video URL",
   "lexical.resize.east": "Resize image to the right",

packages/lexical/src/locales/zh-Hans.ts

@@ -68,18 +68,27 @@ export const messages = {
   "lexical.media.alignLeft": "图片左对齐",
   "lexical.media.alignRight": "图片右对齐",
   "lexical.media.caption": "图片说明",
+  "lexical.media.chooseImageFile": "选择图片",
   "lexical.media.controls": "图片操作",
   "lexical.media.deleteImage": "删除图片",
   "lexical.media.editCaption": "编辑图片说明",
   "lexical.media.imageAlt": "替代文本",
-  "lexical.media.imageAltDescription": "纯装饰图片可以留空；有信息含义时请填写。",
-  "lexical.media.imageDescription": "输入可公开访问的图片地址，并补充替代文本。",
+  "lexical.media.imageAltDescription":
+    "纯装饰图片可以留空；有信息含义时请填写。",
+  "lexical.media.imageDescription":
+    "输入图片地址，或选择本地图片，并补充替代文本。",
+  "lexical.media.imageFile": "图片文件",
+  "lexical.media.imageFileDescription":
+    "从设备选择图片，将以 Base64 Data URL 内嵌到内容中。",
+  "lexical.media.imageFileReadError": "无法读取该图片，请重新选择。",
   "lexical.media.imageUrl": "图片地址",
+  "lexical.media.readingImageFile": "正在读取图片…",
   "lexical.media.uploading": "正在上传图片",
   "lexical.media.uploadingProgress": "正在上传 {progress}%",
   "lexical.media.uploadProgress": "图片上传进度",
   "lexical.media.urlDescription": "支持绝对地址或站内相对地址。",
-  "lexical.media.videoDescription": "输入可公开访问的视频地址；支持浏览器可播放的格式。",
+  "lexical.media.videoDescription":
+    "输入可公开访问的视频地址；支持浏览器可播放的格式。",
   "lexical.media.videoPoster": "视频封面地址",
   "lexical.media.videoUrl": "视频地址",
   "lexical.resize.east": "向右调整图片尺寸",