fix: conditional checks, evershelf.db fix, warning popup 5s, error modal (v1.7.22)

- health_check: use evershelf.db (not dispensa.db); auto-migrate if needed
- removed dispensa.db (legacy, obsolete)
- backups check: verify files exist (not dir writability, cron writes as root)
- bring_token: read data/bring_token.json (not env var)
- warning popup: 5s countdown bar with label+hint per warning, auto-closes
- error popup: blocking panel with title + hint per critical failure
- db_legacy check: warns if old dispensa.db still present
- 32 total checks (added db_legacy, tts_url, scale_gateway)
- hint messages on every check explaining cause and fix
- translations: added check_db_legacy, check_tts, check_scale,
  critical_error_intro, error_network_detail in it/en/de

manifest.json

@@ -2,7 +2,7 @@
     "name": "EverShelf",
     "short_name": "EverShelf",
     "description": "Gestione completa della dispensa di casa con scansione barcode",
-    "version": "1.7.20",
+    "version": "1.7.22",
     "start_url": "/evershelf/",
     "display": "standalone",
     "background_color": "#f0f4e8",