Check translation contracts offline, add Swedish to the installer and enable the website languages

- Offline checks for terminal and website catalogs reject translations that change commands, paths, identifiers or placeholders
- Terminal and documentation texts that broke those contracts are corrected in every language
- Swedish can be chosen in the stable and beta installers
- The website routes, language switcher and exported pages cover the eight languages, with the shared website texts in each of them
- Website documentation translations are generated only when requested
- From PR #475 by @jcastro

web/messages/es/docs/post-install/system.json

@@ -20,7 +20,7 @@
       "<code>SystemMaxUse=64M</code> / <code>RuntimeMaxUse=60M</code> — caps duros sobre el uso de disco/memoria del journal.",
       "<code>Compress=yes</code>, <code>Seal=no</code> — comprimir logs, saltar el forward-secure sealing (ahorra CPU).",
       "<code>MaxLevelStore=info</code> — almacenar info y superiores (requerido para el visor de logs del ProxMenux Monitor y para que Fail2Ban detecte fallos de autenticación SSH/Proxmox desde el journal).",
-      "Rate-limits: <code>1000 eventos / 30 s</code> para prevenir flooding de logs.",
+      "Límite de frecuencia: <code>1000 events / 30 s</code> para evitar una avalancha de registros.",
       "<code>ForwardToSyslog=no</code>, <code>ForwardToWall=no</code> — no duplicar mensajes a syslog ni broadcastear a consolas."
     ],
     "tipTitle": "Por qué importa MaxLevelStore=info",