Fix 40+ bugs from audit passes 9-12

- PNG chunk parsing overflow protection with checked arithmetic
- Font directory traversal bounded with global result limit
- find_unique_path TOCTOU race fixed with create_new + marker byte
- Watch mode "processed" dir exclusion narrowed to prevent false skips
- Metadata copy now checks format support before little_exif calls
- Clipboard temp files cleaned up on app exit
- Atomic writes for file manager integration scripts
- BMP format support added to encoder and convert step
- Regex DoS protection with DFA size limit
- Watermark NaN/negative scale guard
- Selective EXIF stripping for privacy/custom metadata modes
- CLI watch mode: file stability checks, per-file history saves
- High contrast toggle preserves and restores original theme
- Image list deduplication uses O(1) HashSet lookups
- Saturation/trim/padding overflow guards in adjustments

pixstrip-gtk/src/steps/step_compress.rs

@@ -782,7 +782,7 @@ pub fn build_compress_page(state: &AppState) -> adw::NavigationPage {
         .child(&scrolled)
         .build();
 
-    // On page map: refresh preview and show/hide per-format rows
+    // On page map: refresh thumbnail strip, preview, and show/hide per-format rows
     {
         let up = update_preview.clone();
         let jc = state.job_config.clone();
@@ -793,7 +793,71 @@ pub fn build_compress_page(state: &AppState) -> adw::NavigationPage {
         let wer = webp_effort_row;
         let ar = avif_row;
         let asr = avif_speed_row;
+        let lf = state.loaded_files.clone();
+        let tb = thumb_box.clone();
+        let ts = thumb_scrolled.clone();
+        let pidx = preview_index.clone();
+        let up2 = update_preview.clone();
         page.connect_map(move |_| {
+            // Rebuild thumbnail strip from current file list
+            while let Some(child) = tb.first_child() {
+                tb.remove(&child);
+            }
+            let files = lf.borrow();
+            let max_thumbs = files.len().min(10);
+            for i in 0..max_thumbs {
+                let pic = gtk::Picture::builder()
+                    .content_fit(gtk::ContentFit::Cover)
+                    .width_request(50)
+                    .height_request(50)
+                    .build();
+                pic.set_filename(Some(&files[i]));
+                let frame = gtk::Frame::builder()
+                    .child(&pic)
+                    .build();
+                if i == *pidx.borrow() {
+                    frame.add_css_class("accent");
+                }
+                let pidx_c = pidx.clone();
+                let up_c = up2.clone();
+                let tb_c = tb.clone();
+                let current_idx = i;
+                let btn = gtk::Button::builder()
+                    .child(&frame)
+                    .has_frame(false)
+                    .tooltip_text(files[i].file_name().and_then(|n| n.to_str()).unwrap_or("image"))
+                    .build();
+                btn.connect_clicked(move |_| {
+                    *pidx_c.borrow_mut() = current_idx;
+                    up_c(true);
+                    let mut c = tb_c.first_child();
+                    let mut j = 0usize;
+                    while let Some(w) = c {
+                        if let Some(b) = w.downcast_ref::<gtk::Button>() {
+                            if let Some(f) = b.child().and_then(|c| c.downcast::<gtk::Frame>().ok()) {
+                                if j == current_idx {
+                                    f.add_css_class("accent");
+                                } else {
+                                    f.remove_css_class("accent");
+                                }
+                            }
+                        }
+                        c = w.next_sibling();
+                        j += 1;
+                    }
+                });
+                tb.append(&btn);
+            }
+            ts.set_visible(max_thumbs > 1);
+            // Clamp preview index if files were removed
+            {
+                let mut idx = pidx.borrow_mut();
+                if *idx >= files.len() && !files.is_empty() {
+                    *idx = 0;
+                }
+            }
+            drop(files);
+
             up(true);
 
             let cfg = jc.borrow();
@@ -814,7 +878,7 @@ pub fn build_compress_page(state: &AppState) -> adw::NavigationPage {
                 Some(ImageFormat::Png) => has_png = true,
                 Some(ImageFormat::WebP) => has_webp = true,
                 Some(ImageFormat::Avif) => has_avif = true,
-                Some(ImageFormat::Gif) | Some(ImageFormat::Tiff) => {}
+                Some(ImageFormat::Gif) | Some(ImageFormat::Tiff) | Some(ImageFormat::Bmp) => {}
             }
 
             for (_, &choice_idx) in &cfg.format_mappings {