fix: Ctrl+D deletes char under cursor, only exits on empty input (bash/zsh behaviour)

cli.py

@@ -9557,7 +9557,13 @@ class HermesCLI:
         
         @kb.add('c-d')
         def handle_ctrl_d(event):
-            """Handle Ctrl+D - exit."""
+            """Ctrl+D: delete char under cursor (standard readline behaviour).
+            Only exit when the input is empty — same as bash/zsh.
+            """
+            buf = event.app.current_buffer
+            if buf.text:
+                buf.delete()
+            else:
                 self._should_exit = True
                 event.app.exit()