Add crop/trim/canvas padding to adjustments, wire all sliders to config

Add crop to aspect ratio (8 ratios), trim whitespace, and canvas padding
controls to the adjustments step per design doc. Wire brightness,
contrast, saturation, sharpen, grayscale, and sepia to JobConfig. Add
Select All / Deselect All toolbar buttons to images step. Include new
adjustment operations in output step summary.

pixstrip-gtk/src/app.rs

@@ -21,6 +21,15 @@ pub struct JobConfig {
     // Adjustments
     pub rotation: u32,
     pub flip: u32,
+    pub brightness: i32,
+    pub contrast: i32,
+    pub saturation: i32,
+    pub sharpen: bool,
+    pub grayscale: bool,
+    pub sepia: bool,
+    pub crop_aspect_ratio: u32,
+    pub trim_whitespace: bool,
+    pub canvas_padding: u32,
     // Convert
     pub convert_enabled: bool,
     pub convert_format: Option<pixstrip_core::types::ImageFormat>,
@@ -142,6 +151,15 @@ fn build_ui(app: &adw::Application) {
             allow_upscale: false,
             rotation: 0,
             flip: 0,
+            brightness: 0,
+            contrast: 0,
+            saturation: 0,
+            sharpen: false,
+            grayscale: false,
+            sepia: false,
+            crop_aspect_ratio: 0,
+            trim_whitespace: false,
+            canvas_padding: 0,
             convert_enabled: if remember { sess_state.convert_enabled.unwrap_or(false) } else { false },
             convert_format: None,
             compress_enabled: if remember { sess_state.compress_enabled.unwrap_or(true) } else { true },
@@ -1705,6 +1723,43 @@ fn update_output_summary(ui: &WizardUi) {
             };
             ops.push(fl.to_string());
         }
+        if cfg.brightness != 0 {
+            ops.push(format!("Brightness {:+}", cfg.brightness));
+        }
+        if cfg.contrast != 0 {
+            ops.push(format!("Contrast {:+}", cfg.contrast));
+        }
+        if cfg.saturation != 0 {
+            ops.push(format!("Saturation {:+}", cfg.saturation));
+        }
+        if cfg.sharpen {
+            ops.push("Sharpen".to_string());
+        }
+        if cfg.grayscale {
+            ops.push("Grayscale".to_string());
+        }
+        if cfg.sepia {
+            ops.push("Sepia".to_string());
+        }
+        if cfg.crop_aspect_ratio > 0 {
+            let ratio = match cfg.crop_aspect_ratio {
+                1 => "1:1",
+                2 => "4:3",
+                3 => "3:2",
+                4 => "16:9",
+                5 => "9:16",
+                6 => "3:4",
+                7 => "2:3",
+                _ => "Custom",
+            };
+            ops.push(format!("Crop {}", ratio));
+        }
+        if cfg.trim_whitespace {
+            ops.push("Trim whitespace".to_string());
+        }
+        if cfg.canvas_padding > 0 {
+            ops.push(format!("Padding {}px", cfg.canvas_padding));
+        }
 
         let summary_text = if ops.is_empty() {
             "No operations configured".to_string()