fix(workspace): refine workbench defaults and cursor

Add Quick Commands as the default Workbench tab and update
the default three-column layout proportions to better match
the intended workspace design.

Also fix terminal hover cursor behavior and add locale and
docs updates for the new default interaction.

packages/frontend/src/locales/en-US.json

@@ -1281,6 +1281,7 @@
         "noSession": "No active session",
         "fileManagerHint": "Activate an SSH session to browse remote files.",
         "tabs": {
+          "quickCommands": "Quick Commands",
           "files": "Files",
           "history": "History",
           "editor": "Editor"