feat(split-screen): redesign split screen with free-form panes and pane picker

plugins/ssh-terminal/src/frontend/terminal/Terminal.tsx

@@ -3088,6 +3088,7 @@ const TerminalInner = forwardRef<TerminalHandle, SSHTerminalProps>(
             "BracketLeft",
             "Backslash",
             "Minus",
+            "Enter",
           ];
           if (globalCodes.includes(e.code)) {
             e.stopPropagation();

plugins/ssh-terminal/src/frontend/terminal/TerminalTabContent.tsx

@@ -54,6 +54,7 @@ export function TerminalTabContent({
   label,
   isVisible,
   isFocusedPane,
+  inSplit = false,
   handleRef,
   shell,
 }: TabProps) {
@@ -98,7 +99,7 @@ export function TerminalTabContent({
               initialPath={tab.data?.initialPath ?? tab.initialFilePath}
               title={label}
               showTitle={false}
-              splitScreen={false}
+              splitScreen={inSplit}
               onClose={() => shell.closeTab(tab.id)}
               onTitleChange={
                 host.terminalConfig?.useSSHTitle