fix: final review minors m-1 to m-8

- m-1: the no-change Divi result carries preview_url/edit_url too
- m-2: overview names replace-text's per-page tree_rev
- m-3: divi-shortform documents validation_failed vs not_found for unknown IDs
- m-4: DiviWriter/DiviPageLoader final (no mocks left), neutral NewDraft
  log detail, snapshots are Etappe 4
- m-5: Tested up to 7.1, changelog completed
- m-6: content-create warns when the extras changed the stored layout
- m-7: deleting a whole section outlines nothing instead of the next one
- m-8: uninstall removes the user meta lit_mcp_log_per_page; readme lists it

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01At3V6SjwbMe6eMzVGW3Hs7

src/Integrations/Divi/Pages/DiviPageLoader.php

@@ -18,10 +18,9 @@ defined('ABSPATH') || exit;
 /**
  * Loads an entry for the Divi tools: rights and status via PostGuard (spec §4.5), then the
  * block tree. Divi 4 shortcode content and unbalanced markup are refused with a hint –
- * spec §3.4: Divi 4 content is kept, never edited. Not final so abilities can be tested
- * with a mock.
+ * spec §3.4: Divi 4 content is kept, never edited.
  */
-class DiviPageLoader
+final class DiviPageLoader
 {
     public const OUTLINE_HINT = 'Aktuellen Stand mit lit/divi-outline (direkt: lit-divi-outline) neu lesen und die '
         . 'Änderung mit der neuen tree_rev wiederholen.';