Nitro V3 update: CLI-only (Linux), settings via .env

- Moved Nitro V3 update from web UI (Commandocentrum) to CLI-only
- Removed configure paths form and runUpdateNitrov3() from admin panel
- update-Nitrov3.sh now loads .env automatically from its directory
- Added all NITRO_* env vars to .env.example.linux and .env
- Removed configurable paths from database (replaced by .env)
- Updated README and CHANGELOG

lang/nl.json

@@ -305,19 +305,6 @@
   "radio.wizard.unknown_error": "Onbekende fout",
   "Homepage": "Homepage",
   "commandocentrum.nitro_update": "Nitro V3 Update",
-  "commandocentrum.nitro_update_desc": "Configureer paths en voer het update script uit voor Nitro V3, Render V3 en de Emulator",
-  "commandocentrum.run_update": "Run Update",
-  "commandocentrum.configure_nitro": "Configureer Paths",
-  "commandocentrum.save_nitro_config": "Save Config",
-  "commandocentrum.nitro_config_saved": "Nitro configuratie opgeslagen!",
-  "commandocentrum.nitro_update_output": "Update Output",
-  "commandocentrum.nitro_emulator_path": "Emulator hoofdmap",
-  "commandocentrum.nitro_emulator_service": "Emulator service naam",
-  "commandocentrum.nitro_db_name": "Database naam",
-  "commandocentrum.nitro_sql_dir": "SQL updates map",
-  "commandocentrum.nitro_backup_dir": "Backup map",
-  "commandocentrum.nitro_gamedata_dir": "Gamedata config map",
-  "commandocentrum.nitro_client_dir": "Nitro client config map (public/configuration)",
-  "commandocentrum.nitro_client_src": "Nitro-V3 bronmap",
-  "commandocentrum.nitro_renderer_src": "Nitro Render V3 bronmap"
+  "commandocentrum.nitro_update_desc": "Update alleen via command line — configureer instellingen in .env",
+  "commandocentrum.nitro_cli_only": "Dit script kan alleen via de command line worden uitgevoerd. Gebruik: bash update-Nitrov3.sh\n\nInstellingen worden geconfigureerd in het .env bestand in de project root."
 }