Rename Copy to Send and put it first in the row context menu

The main feature (copy selection to the other panel, F5) is now labeled
"Send" in the toolbar button, tooltips, and context menu across all 7
locales. Internal identifiers (copyToOtherPanel, ctx-copy, i18n keys)
and secondary strings (toasts, status bar, errors) are unchanged.
The context-menu entry moves ahead of Open/Edit as the first row item.
README, marketing site, and the Windows QA checklist updated to match.

Co-Authored-By: Claude <noreply@anthropic.com>

src/shared/i18n/ja.ts

@@ -79,9 +79,9 @@ export const ja = {
 	},
 	panel: {
 		choosePanel: "このパネルに表示する内容を選択",
-		copy: "コピー",
-		copyToRight: "右のパネルへコピー (F5)",
-		copyToLeft: "左のパネルへコピー (F5)",
+		copy: "送信",
+		copyToRight: "右のパネルへ送信 (F5)",
+		copyToLeft: "左のパネルへ送信 (F5)",
 		edit: "編集",
 		editFile: "ファイルを編集 (F4)",
 		rename: "名前を変更 (F2)",
@@ -282,7 +282,7 @@ export const ja = {
 		open: "開く",
 		openDefault: "既定のアプリで開く",
 		edit: "編集",
-		copyToOther: "もう一方のパネルへコピー",
+		copyToOther: "もう一方のパネルへ送信",
 		rename: "名前を変更",
 		permissions: "アクセス権",
 		copyPath: "パスをコピー",