Add Adjustments, Watermark, Rename wizard steps; expand to 10-step wizard

- New step_adjustments: rotation (5 options) and flip (3 options)
- New step_watermark: text/image watermark with position, opacity, font size
- New step_rename: prefix/suffix/counter with live preview and template engine
- Updated step_metadata: added Custom mode with per-category checkboxes
  (GPS, camera, software, timestamps, copyright) with show/hide toggle
- Expanded JobConfig with all operation fields (watermark, rename, metadata custom)
- Updated wizard from 7 to 10 steps in correct pipeline order
- Fixed page index references from 6 to 9 for output step
- Added MetadataMode::Custom handling in preset builder and output summary

pixstrip-gtk/src/steps/step_adjustments.rs

@@ -0,0 +1,87 @@
+use adw::prelude::*;
+use crate::app::AppState;
+
+pub fn build_adjustments_page(state: &AppState) -> adw::NavigationPage {
+    let scrolled = gtk::ScrolledWindow::builder()
+        .hscrollbar_policy(gtk::PolicyType::Never)
+        .vexpand(true)
+        .build();
+
+    let content = gtk::Box::builder()
+        .orientation(gtk::Orientation::Vertical)
+        .spacing(12)
+        .margin_top(12)
+        .margin_bottom(12)
+        .margin_start(24)
+        .margin_end(24)
+        .build();
+
+    let cfg = state.job_config.borrow();
+
+    // Rotate
+    let rotate_group = adw::PreferencesGroup::builder()
+        .title("Rotation")
+        .build();
+
+    let rotate_row = adw::ComboRow::builder()
+        .title("Rotate")
+        .subtitle("Rotation applied after resize")
+        .build();
+    let rotate_model = gtk::StringList::new(&[
+        "None",
+        "90 clockwise",
+        "180",
+        "270 clockwise",
+        "Auto-orient (EXIF)",
+    ]);
+    rotate_row.set_model(Some(&rotate_model));
+    rotate_row.set_selected(cfg.rotation);
+
+    rotate_group.add(&rotate_row);
+    content.append(&rotate_group);
+
+    // Flip
+    let flip_group = adw::PreferencesGroup::builder()
+        .title("Flip")
+        .build();
+
+    let flip_row = adw::ComboRow::builder()
+        .title("Flip")
+        .subtitle("Mirror the image")
+        .build();
+    let flip_model = gtk::StringList::new(&["None", "Horizontal", "Vertical"]);
+    flip_row.set_model(Some(&flip_model));
+    flip_row.set_selected(cfg.flip);
+
+    flip_group.add(&flip_row);
+    content.append(&flip_group);
+
+    drop(cfg);
+
+    // Wire signals
+    {
+        let jc = state.job_config.clone();
+        rotate_row.connect_selected_notify(move |row| {
+            jc.borrow_mut().rotation = row.selected();
+        });
+    }
+    {
+        let jc = state.job_config.clone();
+        flip_row.connect_selected_notify(move |row| {
+            jc.borrow_mut().flip = row.selected();
+        });
+    }
+
+    scrolled.set_child(Some(&content));
+
+    let clamp = adw::Clamp::builder()
+        .maximum_size(600)
+        .child(&scrolled)
+        .build();
+
+    adw::NavigationPage::builder()
+        .title("Adjustments")
+        .tag("step-adjustments")
+        .child(&clamp)
+        .build()
+}