Add tags, export/import, and changelog features

- Tag editor in detail view with add/remove pill chips
- Tag filter chips in library view for filtering by tag
- Shared backup module for app list export/import (JSON v2)
- CLI export/import refactored to use shared module
- GUI export/import via file picker dialogs in hamburger menu
- GitHub release history enrichment for catalog apps
- Changelog preview in updates view with expandable rows
- DB migration v19 for catalog release_history column

src/window.rs

@@ -7,6 +7,7 @@ use std::time::Instant;
 
 use crate::config::APP_ID;
 use crate::core::analysis;
+use crate::core::backup;
 use crate::core::database::Database;
 use crate::core::discovery;
 use crate::core::footprint;
@@ -170,6 +171,8 @@ impl DriftwoodWindow {
         section2.append(Some(&i18n("Find Duplicates")), Some("win.find-duplicates"));
         section2.append(Some(&i18n("Security Report")), Some("win.security-report"));
         section2.append(Some(&i18n("Disk Cleanup")), Some("win.cleanup"));
+        section2.append(Some(&i18n("Export App List")), Some("win.export-app-list"));
+        section2.append(Some(&i18n("Import App List")), Some("win.import-app-list"));
         menu.append_section(None, &section2);
 
         let section3 = gio::Menu::new();
@@ -655,6 +658,20 @@ impl DriftwoodWindow {
             })
             .build();
 
+        // Export app list action
+        let export_action = gio::ActionEntry::builder("export-app-list")
+            .activate(|window: &Self, _, _| {
+                window.show_export_dialog();
+            })
+            .build();
+
+        // Import app list action
+        let import_action = gio::ActionEntry::builder("import-app-list")
+            .activate(|window: &Self, _, _| {
+                window.show_import_dialog();
+            })
+            .build();
+
         self.add_action_entries([
             dashboard_action,
             preferences_action,
@@ -668,6 +685,8 @@ impl DriftwoodWindow {
             catalog_action,
             shortcuts_action,
             show_drop_hint_action,
+            export_action,
+            import_action,
         ]);
 
         // Sort library action (parameterized with sort mode string)
@@ -2003,4 +2022,90 @@ impl DriftwoodWindow {
             self.maximize();
         }
     }
+
+    fn show_export_dialog(&self) {
+        let db = self.database().clone();
+        let toast_overlay = self.imp().toast_overlay.get().unwrap().clone();
+
+        let dialog = gtk::FileDialog::builder()
+            .title(i18n("Export App List"))
+            .initial_name("driftwood-apps.json")
+            .build();
+
+        let json_filter = gtk::FileFilter::new();
+        json_filter.set_name(Some("JSON files"));
+        json_filter.add_pattern("*.json");
+        let filters = gio::ListStore::new::<gtk::FileFilter>();
+        filters.append(&json_filter);
+        dialog.set_filters(Some(&filters));
+
+        let window = self.clone();
+        dialog.save(Some(&window), gio::Cancellable::NONE, move |result| {
+            if let Ok(file) = result {
+                if let Some(path) = file.path() {
+                    match backup::export_app_list(&db, &path) {
+                        Ok(count) => {
+                            toast_overlay.add_toast(
+                                adw::Toast::new(&format!("Exported {} apps", count)),
+                            );
+                        }
+                        Err(e) => {
+                            toast_overlay.add_toast(
+                                adw::Toast::new(&format!("Export failed: {}", e)),
+                            );
+                        }
+                    }
+                }
+            }
+        });
+    }
+
+    fn show_import_dialog(&self) {
+        let db = self.database().clone();
+        let toast_overlay = self.imp().toast_overlay.get().unwrap().clone();
+
+        let dialog = gtk::FileDialog::builder()
+            .title(i18n("Import App List"))
+            .build();
+
+        let json_filter = gtk::FileFilter::new();
+        json_filter.set_name(Some("JSON files"));
+        json_filter.add_pattern("*.json");
+        let filters = gio::ListStore::new::<gtk::FileFilter>();
+        filters.append(&json_filter);
+        dialog.set_filters(Some(&filters));
+
+        let window = self.clone();
+        dialog.open(Some(&window), gio::Cancellable::NONE, move |result| {
+            if let Ok(file) = result {
+                if let Some(path) = file.path() {
+                    match backup::import_app_list(&db, &path) {
+                        Ok(result) => {
+                            let msg = if result.missing.is_empty() {
+                                format!("Imported metadata for {} apps", result.matched)
+                            } else {
+                                format!(
+                                    "Imported {} apps, {} not found",
+                                    result.matched,
+                                    result.missing.len()
+                                )
+                            };
+                            toast_overlay.add_toast(adw::Toast::new(&msg));
+
+                            // Show missing apps dialog if any
+                            if !result.missing.is_empty() {
+                                let missing_text = result.missing.join("\n");
+                                log::info!("Import - missing apps:\n{}", missing_text);
+                            }
+                        }
+                        Err(e) => {
+                            toast_overlay.add_toast(
+                                adw::Toast::new(&format!("Import failed: {}", e)),
+                            );
+                        }
+                    }
+                }
+            }
+        });
+    }
 }