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/analysis.rs

@@ -61,7 +61,7 @@ pub fn run_background_analysis(id: i64, path: PathBuf, appimage_type: AppImageTy
         log::warn!("Failed to set analysis status to 'analyzing' for id {}: {}", id, e);
     }
 
-    // Inspect metadata (app name, version, icon, desktop entry, etc.)
+    // Inspect metadata (app name, version, icon, desktop entry, AppStream, etc.)
     if let Ok(meta) = inspector::inspect_appimage(&path, &appimage_type) {
         let categories = if meta.categories.is_empty() {
             None
@@ -84,6 +84,61 @@ pub fn run_background_analysis(id: i64, path: PathBuf, appimage_type: AppImageTy
         ) {
             log::warn!("Failed to update metadata for id {}: {}", id, e);
         }
+
+        // Store extended metadata from AppStream XML and desktop entry
+        let keywords = if meta.keywords.is_empty() {
+            None
+        } else {
+            Some(meta.keywords.join(","))
+        };
+        let mime_types = if meta.mime_types.is_empty() {
+            None
+        } else {
+            Some(meta.mime_types.join(";"))
+        };
+        let release_json = if meta.releases.is_empty() {
+            None
+        } else {
+            let releases: Vec<serde_json::Value> = meta
+                .releases
+                .iter()
+                .map(|r| {
+                    serde_json::json!({
+                        "version": r.version,
+                        "date": r.date,
+                        "description": r.description,
+                    })
+                })
+                .collect();
+            Some(serde_json::to_string(&releases).unwrap_or_default())
+        };
+        let actions_json = if meta.desktop_actions.is_empty() {
+            None
+        } else {
+            Some(serde_json::to_string(&meta.desktop_actions).unwrap_or_default())
+        };
+
+        if let Err(e) = db.update_appstream_metadata(
+            id,
+            meta.appstream_id.as_deref(),
+            meta.appstream_description.as_deref(),
+            meta.generic_name.as_deref(),
+            meta.license.as_deref(),
+            meta.homepage_url.as_deref(),
+            meta.bugtracker_url.as_deref(),
+            meta.donation_url.as_deref(),
+            meta.help_url.as_deref(),
+            meta.vcs_url.as_deref(),
+            keywords.as_deref(),
+            mime_types.as_deref(),
+            meta.content_rating.as_deref(),
+            meta.project_group.as_deref(),
+            release_json.as_deref(),
+            actions_json.as_deref(),
+            meta.has_signature,
+        ) {
+            log::warn!("Failed to update appstream metadata for id {}: {}", id, e);
+        }
     }
 
     // FUSE status