Frontend audit: refinements (#2083)

* (fix:attachements) sep id for redux ops

* (fix:ui) popups, toast, share modal

* (feat:agentsPreview) stable preview, ui fixes

* (fix:ui) light theme icon, sleek scroll

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Co-authored-by: GH Action - Upstream Sync <action@github.com>

frontend/src/locale/jp.json

@@ -384,7 +384,8 @@
       "title": "ソース",
       "text": "ソーステキスト",
       "link": "ソースリンク",
-      "view_more": "さらに{{count}}個のソース"
+      "view_more": "さらに{{count}}個のソース",
+      "noSourcesAvailable": "利用可能なソースがありません"
     },
     "attachments": {
       "attach": "添付",