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>

site/index.html

@@ -169,10 +169,10 @@
   <hr>
   <h2 id="different">Same tool you know, only a little different</h2>
   <p>If you've ever used a two-pane file manager to move files over SFTP, you already know how to
-    use miniSCP. Two panels, a connection on each side, copy between them. Nothing to relearn.</p>
+    use miniSCP. Two panels, a connection on each side, send between them. Nothing to relearn.</p>
 
   <p>The difference is in the corners. Both panels are fully symmetric &mdash; either side can be
-    your local disk or any saved server &mdash; so a copy isn't only up or down. You can move files
+    your local disk or any saved server &mdash; so sending isn't only up or down. You can move files
     <b>straight from one server to another</b>, remote to remote, without staging them on your
     machine first.
   </p>
@@ -183,7 +183,7 @@
 
   <p><b>What's different:</b></p>
 
-  <p class="feat"><b>Remote &rarr; remote.</b> Copy straight between two servers &mdash; nothing
+  <p class="feat"><b>Remote &rarr; remote.</b> Send straight between two servers &mdash; nothing
     staged on your machine.</p>
   <p class="feat"><b>Symmetric panels.</b> Either side is your local disk or any saved server. Every
     panel is equal.</p>