Add WebP effort, AVIF speed controls, case conversion and regex rename

- Compress step: WebP Encoding Effort (0-6) and AVIF Encoding Speed (1-10)
- Rename step: Case Conversion combo (lowercase/UPPERCASE/Title Case)
- Rename step: Find and Replace group with regex pattern and replacement

pixstrip-gtk/src/steps/step_rename.rs

@@ -121,9 +121,34 @@ pub fn build_rename_page(state: &AppState) -> adw::NavigationPage {
         .margin_start(12)
         .build();
 
+    let case_row = adw::ComboRow::builder()
+        .title("Case Conversion")
+        .subtitle("Convert filename case")
+        .build();
+    let case_model = gtk::StringList::new(&["No change", "lowercase", "UPPERCASE", "Title Case"]);
+    case_row.set_model(Some(&case_model));
+
+    let regex_group = adw::PreferencesGroup::builder()
+        .title("Find and Replace")
+        .description("Regex find-and-replace on original filename")
+        .build();
+
+    let find_row = adw::EntryRow::builder()
+        .title("Find (regex)")
+        .build();
+
+    let replace_row = adw::EntryRow::builder()
+        .title("Replace with")
+        .build();
+
+    regex_group.add(&find_row);
+    regex_group.add(&replace_row);
+
     advanced_group.add(&template_row);
     advanced_group.add(&help_label);
+    advanced_group.add(&case_row);
     content.append(&advanced_group);
+    content.append(&regex_group);
 
     drop(cfg);