chore: release v1.7.1

- Bump header-version in index.html to v1.7.1
- Bump manifest.json version to 1.7.1
- Update CHANGELOG with v1.7.1 release notes

Includes:
- Destructive confirm modal with 5s auto-countdown (throwAll, submitUseAll)
- Undo button visibility fix in history log
- undoTransactionEntry() uses custom modal instead of native confirm()

manifest.json

@@ -2,7 +2,7 @@
     "name": "EverShelf",
     "short_name": "EverShelf",
     "description": "Gestione completa della dispensa di casa con scansione barcode",
-    "version": "1.5.0",
+    "version": "1.7.1",
     "start_url": "/evershelf/",
     "display": "standalone",
     "background_color": "#f0f4e8",