feat: add xmlsvg export option (#761)

* feat: add xmlsvg export option

* fix: avoid atob for xmlsvg export to prevent UTF-8 corruption

Pass the data URL directly (like PNG export) instead of decoding
with atob(). atob() + Blob([string]) double-encodes non-ASCII
characters (Chinese, Japanese, emoji), corrupting the output file.

---------

Co-authored-by: dayuan.jiang <jdy.toh@gmail.com>

lib/i18n/dictionaries/en.json

@@ -140,7 +140,8 @@
         "formats": {
             "drawio": "Draw.io XML",
             "png": "PNG Image",
-            "svg": "SVG Image"
+            "svg": "SVG Image",
+            "xmlsvg": "Editable SVG"
         },
         "savedSuccessfully": "Saved successfully!"
     },

lib/i18n/dictionaries/ja.json

@@ -140,7 +140,8 @@
         "formats": {
             "drawio": "Draw.io XML",
             "png": "PNG 画像",
-            "svg": "SVG 画像"
+            "svg": "SVG 画像",
+            "xmlsvg": "編集可能 SVG"
         },
         "savedSuccessfully": "保存完了！"
     },

lib/i18n/dictionaries/zh-Hant.json

@@ -140,7 +140,8 @@
         "formats": {
             "drawio": "Draw.io XML",
             "png": "PNG 圖片",
-            "svg": "SVG 圖片"
+            "svg": "SVG 圖片",
+            "xmlsvg": "可編輯 SVG"
         },
         "savedSuccessfully": "儲存成功！"
     },

lib/i18n/dictionaries/zh.json

@@ -140,7 +140,8 @@
         "formats": {
             "drawio": "Draw.io XML",
             "png": "PNG 图片",
-            "svg": "SVG 图片"
+            "svg": "SVG 图片",
+            "xmlsvg": "可编辑 SVG"
         },
         "savedSuccessfully": "保存成功！"
     },