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>

README.md

@@ -22,7 +22,7 @@ Dense reference material lives in [docs/](docs/): [architecture](docs/architectu
 - Dual-panel commander UI; either panel can be Local or any saved connection.
 - **Session tabs**: each tab is an independent left/right workspace; remote
   sessions stay connected and transfers keep running in background tabs.
-- Per-panel action toolbar with a direction-explicit copy button, plus a
+- Per-panel action toolbar with a direction-explicit send button, plus a
   VSCode-style status bar showing live transfer progress (click to expand the
   transfer queue with per-file speed and ETA).
 - **Overwrite confirmation** on name collisions, with a source-vs-destination
@@ -42,7 +42,7 @@ Dense reference material lives in [docs/](docs/): [architecture](docs/architectu
   cleanup at the next start.
 - Browse, sort (name/size/modified, folders first), keyboard navigation.
 - Create folder / file, rename, delete (recursive), change permissions (chmod).
-- Upload, download, and remote→remote copy — files **and** whole folders —
+- Upload, download, and remote→remote send — files **and** whole folders —
   with a transfer queue, per-job progress, and cancel.
 - Connection manager: saved connections organised into folders, password or
   private-key auth (with passphrase).
@@ -170,7 +170,7 @@ Saved connections live in a plain JSON file in the OS app-data directory
 
 `Tab` switch panel · `↑`/`↓`/`PgUp`/`PgDn`/`Home`/`End` move cursor ·
 `Space` select · `Enter` open folder · `Backspace` parent ·
-`Ctrl/Cmd+A` select all · `F5` copy to other panel · `F2` rename ·
+`Ctrl/Cmd+A` select all · `F5` send to other panel · `F2` rename ·
 `F7` new folder · `F8`/`Delete` delete · `Cmd/Ctrl+T` new tab ·
 `Cmd/Ctrl+W` close tab · `Ctrl+Tab` next tab.