Fix cursor positioning after command execution

- Cursor now automatically moves to end of prompt after Enter
- Text view becomes first responder automatically
- No need to click to start typing after command execution

TerminalSession.swift

@@ -199,6 +199,10 @@ class TerminalSession: NSObject, NSTextViewDelegate, NSMenuDelegate {
     func showPrompt() {
         appendText("$ ")
         promptPosition = textView.string.count
+        
+        // Move cursor to end and make text view first responder
+        textView.setSelectedRange(NSRange(location: textView.string.count, length: 0))
+        textView.window?.makeFirstResponder(textView)
     }
     
     func appendText(_ text: String) {