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/window.rs

@@ -876,7 +876,12 @@ impl DriftwoodWindow {
                         let mtime_unchanged = modified.as_deref() == ex.file_modified.as_deref();
                         let analysis_done = ex.analysis_status.as_deref() == Some("complete");
                         let has_icon = ex.icon_path.is_some();
-                        if size_unchanged && mtime_unchanged && analysis_done && has_icon {
+                        // Also re-analyze if AppStream metadata was never extracted
+                        // (covers upgrades from older schema versions)
+                        let has_appstream = ex.appstream_id.is_some()
+                            || ex.generic_name.is_some()
+                            || ex.has_signature;
+                        if size_unchanged && mtime_unchanged && analysis_done && has_icon && has_appstream {
                             skipped_count += 1;
                             continue;
                         }
@@ -965,9 +970,13 @@ impl DriftwoodWindow {
                             }
 
                             let window_weak4 = window_weak3.clone();
+                            let refresh_timer_clear = refresh_timer.clone();
                             let timer_id = glib::timeout_add_local_once(
                                 std::time::Duration::from_millis(300),
                                 move || {
+                                    // Clear the stored SourceId so nobody tries to remove a fired timer
+                                    refresh_timer_clear.set(None);
+
                                     if let Some(window) = window_weak4.upgrade() {
                                         let db = window.database();
                                         let lib_view = window.imp().library_view.get().unwrap();