feat: Add web UI for manual oneliner overrides

Adds a new POST endpoint for web-based oneliner overrides and updates
the UI to allow manual editing. The person icon replaces the pencil icon
for doctor-authored titles, signifying manual authorship rather than
editability.

client-desktop/src/app.rs

@@ -622,7 +622,13 @@ impl DoctateApp {
                         };
                         let resp = ui.add(label);
                         if matches!(marker.oneliner, Some(OnelinerState::Manual { .. })) {
-                            ui.colored_label(egui::Color32::from_rgb(0, 110, 0), "✏");
+                            // Person-glyph marks doctor-authored titles.
+                            // Replaces an earlier pencil icon: the pencil
+                            // suggested an edit affordance, but on this row
+                            // the marker is informational only — clicking
+                            // the title text already opens the editor.
+                            ui.colored_label(egui::Color32::GRAY, "👤")
+                                .on_hover_text("manuell bearbeitet");
                         }
                         if resp.clicked() {
                             // Pre-fill the editor with the visible text