Add verified Dev Brain skills

src/app/view/preferences.rs

@@ -180,6 +180,18 @@ impl App {
                 .align_y(Alignment::Center),
                 text("The folder must already contain .obsidian. DS4Server manages only its declared wiki pages and leaves settings, attachments, hidden files, and unrelated notes untouched.")
                     .size(12),
+                row![
+                    text("Restore the current built-in Dev Brain guidance after an upgrade.")
+                        .size(12)
+                        .width(Length::Fill),
+                    hint(
+                        action_button("Recreate purpose.md and schema.md")
+                            .on_press(Message::RestoreDevBrainDefaultGuides),
+                        "Overwrites only purpose.md and schema.md with this version's defaults. Topic pages, generated indexes, and log.md are preserved.",
+                    ),
+                ]
+                .spacing(12)
+                .align_y(Alignment::Center),
             ]
             .spacing(10),
         );