Fix line-based editing behavior for cut and duplicate commands

- Cut to temp buffer:
  - Respect selections by expanding to full line boundaries
  - Normalize end iterator to include full line + newline
  - Ensure consistent newline handling for last line
  - Preserve cursor position after delete
  - Prevent line merging when accumulating cut buffer

- Duplicate line:
  - Simplify logic using line-based iter APIs
  - Fix incorrect selection handling and off-by-one issues
  - Ensure full-line duplication for both selection and cursor cases
  - Correct cursor/selection restoration after duplication

plugins/code/commands/nanoesq_temp_buffer/cut_to_temp_buffer.py

@@ -14,31 +14,44 @@ from .helpers import clear_temp_cut_buffer_delayed, set_temp_cut_buffer_delayed
 
 class Handler:
     @staticmethod
-    def execute(
-        view: GtkSource.View,
-        *args,
-        **kwargs
-    ):
+    def execute(view: GtkSource.View, *args, **kwargs):
         logger.debug("Command: Cut to Temp Buffer")
 
         clear_temp_cut_buffer_delayed(view)
 
         buffer = view.get_buffer()
-        itr = buffer.get_iter_at_mark(buffer.get_insert())
 
-        start_itr = itr.copy()
-        start_itr.set_line_offset(0)
+        if buffer.get_has_selection():
+            start_itr, end_itr = buffer.get_selection_bounds()
 
-        end_itr = start_itr.copy()
-        if not end_itr.forward_line():
-            end_itr = buffer.get_end_iter()
+            start_itr.set_line_offset(0)
+
+            if not end_itr.ends_line():
+                end_itr.forward_to_line_end()
+
+            if not end_itr.is_end():
+                end_itr.forward_char()
+        else:
+            itr = buffer.get_iter_at_mark(buffer.get_insert())
+
+            start_itr = itr.copy()
+            start_itr.set_line_offset(0)
+
+            end_itr = start_itr.copy()
+            if not end_itr.forward_line():
+                end_itr = buffer.get_end_iter()
 
         if not hasattr(view, "_cut_buffer"):
             view._cut_buffer = ""
 
-        line_str = buffer.get_text(start_itr, end_itr, True)
-        view._cut_buffer += line_str
+        text = buffer.get_text(start_itr, end_itr, True)
+
+        if not text.endswith("\n"):
+            text += "\n"
+
+        view._cut_buffer += text
 
         buffer.delete(start_itr, end_itr)
+        buffer.place_cursor(start_itr)
 
-        set_temp_cut_buffer_delayed(view)
+        set_temp_cut_buffer_delayed(view)