feat: progress bar startup check with 29 diagnostics (v1.7.21)

- Replace banner checklist with real-time progress bar + per-check label
  Bar fills smoothly (0→100%) as each check runs; label shows current check.
  On success: bar stays green briefly then fades. On warnings: amber badges
  shown for 2.2s. On critical error: bar turns red + error block + Retry.
- Extend health_check to 29 comprehensive checks:
  PHP 8.0+ version, 4 critical extensions (pdo_sqlite/curl/json/mbstring),
  4 optional extensions (openssl/fileinfo/zip/intl), PHP memory/timeout/upload,
  data/ writable, rate_limits/ dir, backups/ dir, actual file-write test,
  free disk space, SQLite connect, required tables, PRAGMA quick_check integrity,
  WAL mode, DB file size, inventory row count, .env file, Gemini AI key,
  Bring! credentials + token, cURL SSL version, internet reachability (Gemini API)
- Fresh-install detection: if dispensa.db not found + data/ writable → OK (auto-create)
- Translations: startup.* expanded to 28 keys in IT, EN, DE, FR, ES
- CSS: new .preloader-progress-wrap, .preloader-bar-track, .preloader-bar,
  .preloader-check-label, .preloader-warn-badge; removed old .preloader-checks
- Version: v1.7.21, assets v=20260520b

translations/es.json

@@ -1203,15 +1203,33 @@
     "btn_title": "Exportar"
   },
   "startup": {
-    "check_php": "PHP",
-    "check_exts": "Extensiones PHP",
+    "connecting": "Conectando al servidor...",
+    "check_php_memory": "Memoria PHP",
+    "check_php_timeout": "Tiempo de espera PHP",
+    "check_php_upload": "Upload PHP",
     "check_data_dir": "Carpeta de datos",
-    "check_db": "Base de datos",
-    "check_env": "Configuración (.env)",
+    "check_rate_limits": "Dir. rate limits",
+    "check_backups": "Dir. copias de seguridad",
+    "check_write_test": "Prueba escritura disco",
+    "check_disk_space": "Espacio en disco",
+    "check_db_connect": "Conexión base de datos",
+    "check_db_tables": "Tablas de la BD",
+    "check_db_integrity": "Integridad BD",
+    "check_db_wal": "Modo WAL",
+    "check_db_size": "Tamaño de la BD",
+    "check_db_rows": "Datos del inventario",
+    "check_env": "Archivo .env",
     "check_gemini": "Clave Gemini AI",
-    "check_bring": "Token de Bring!",
+    "check_bring_creds": "Credenciales Bring!",
+    "check_bring_token": "Token de Bring!",
+    "check_curl_ssl": "cURL SSL",
+    "check_internet": "Conexión a internet",
+    "fresh_install": "instalación nueva",
+    "warnings_found": "avisos detectados",
+    "all_ok": "Sistema OK",
+    "critical_error_short": "Error crítico",
     "critical_error": "Error crítico: la aplicación no puede iniciarse. Revisa los registros del servidor.",
-    "error_network": "No se puede contactar con el servidor. Comprueba tu conexión.",
+    "error_network": "No se puede contactar con el servidor. Comprueba tu conexión de red.",
     "retry": "Reintentar"
   }
 }