Fix pipeline order, add selective metadata stripping, rename case/regex

- Move watermark step after compress in processing pipeline to match
  design doc order (resize, adjustments, convert, compress, metadata,
  watermark, rename)
- Implement selective EXIF metadata stripping for Privacy and Custom
  modes using little_exif tag filtering (GPS, camera, software,
  timestamps, copyright categories)
- Add case conversion support to rename (none/lower/upper/title)
- Add regex find-and-replace on original filenames
- Wire case and regex controls in rename step UI to JobConfig
- Add regex crate dependency to pixstrip-core

pixstrip-gtk/src/steps/step_rename.rs

@@ -264,6 +264,9 @@ pub fn build_rename_page(state: &AppState) -> adw::NavigationPage {
                             counter_start: cfg.rename_counter_start,
                             counter_padding: cfg.rename_counter_padding,
                             template: None,
+                            case_mode: cfg.rename_case,
+                            regex_find: cfg.rename_find.clone(),
+                            regex_replace: cfg.rename_replace.clone(),
                         };
                         let result =
                             rename_cfg.apply_simple(name, ext, (i + 1) as u32);
@@ -319,12 +322,36 @@ pub fn build_rename_page(state: &AppState) -> adw::NavigationPage {
     }
     {
         let jc = state.job_config.clone();
-        let up = update_preview;
+        let up = update_preview.clone();
         template_row.connect_changed(move |row| {
             jc.borrow_mut().rename_template = row.text().to_string();
             up();
         });
     }
+    {
+        let jc = state.job_config.clone();
+        let up = update_preview.clone();
+        case_row.connect_selected_notify(move |row| {
+            jc.borrow_mut().rename_case = row.selected();
+            up();
+        });
+    }
+    {
+        let jc = state.job_config.clone();
+        let up = update_preview.clone();
+        find_row.connect_changed(move |row| {
+            jc.borrow_mut().rename_find = row.text().to_string();
+            up();
+        });
+    }
+    {
+        let jc = state.job_config.clone();
+        let up = update_preview;
+        replace_row.connect_changed(move |row| {
+            jc.borrow_mut().rename_replace = row.text().to_string();
+            up();
+        });
+    }
 
     scrolled.set_child(Some(&content));