Add comprehensive AppImage metadata extraction, display, and bug fixes

- Add AppStream XML parser (quick-xml) to extract rich metadata from bundled
  metainfo/appdata files: description, developer, license, URLs, keywords,
  categories, content rating, release history, and MIME types
- Database migration v9: 16 new columns for extended metadata storage
- Extended inspector to parse AppStream XML, desktop entry extended fields,
  and detect binary signatures without executing AppImages
- Redesigned detail view overview tab with 8 conditional groups: About,
  Description, Links, Release History, Usage, Capabilities, File Info
- Fix crash on exit caused by stale GLib SourceId removal in debounce timers
- Fix wayland.rs executing AppImages directly to detect squashfs offset,
  replaced with safe binary scan via find_squashfs_offset_for()
- Fix scan skipping re-analysis of apps missing new metadata fields

src/core/wayland.rs

@@ -130,17 +130,11 @@ pub fn analyze_appimage(appimage_path: &Path) -> WaylandAnalysis {
 
 /// List shared libraries bundled inside the AppImage squashfs.
 fn list_bundled_libraries(appimage_path: &Path) -> Vec<String> {
-    // First get the squashfs offset
-    let offset_output = Command::new(appimage_path)
-        .arg("--appimage-offset")
-        .env("APPIMAGE_EXTRACT_AND_RUN", "1")
-        .output();
-
-    let offset = match offset_output {
-        Ok(out) if out.status.success() => {
-            String::from_utf8_lossy(&out.stdout).trim().to_string()
-        }
-        _ => return Vec::new(),
+    // Get the squashfs offset using binary scan (never execute the AppImage -
+    // some apps like Affinity have custom AppRun scripts that ignore flags)
+    let offset = match crate::core::inspector::find_squashfs_offset_for(appimage_path) {
+        Some(o) => o.to_string(),
+        None => return Vec::new(),
     };
 
     // Use unsquashfs to list files (just filenames, no extraction)