fix(kernsheet): clear the terminal on within-score review-walk advance

Pressing 'n' to step to the next flagged page reprinted the landing header
below any prior 't'/'k' dump instead of on a clean screen. Clear and reprint
the id/progress/status header, matching fresh score entry.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01QdzXhuVaZRjT4oXShXm8Dz

Author: anselm67

src/kernsheet/editor.py

@@ -809,6 +809,8 @@ def edit(
                     self.page_index = nxt
                     self._reset_selection()
                     self._select_flagged_system()
+                    self.clear()  # wipe any 't'/'k' dump before the new landing
+                    print(f"id : {self.id}")
                     self.print_review_progress()
                     self.print_page_status()
                     continue