fix: NetBird je samostatna aplikace (apt balicek), ne Docker sluzba

roles/netbird/tasks/main.yml:
- apt balicek 'netbird' (oficialni NetBird Linux klient)
- neni Docker, neni sluzba - je to VPN klient

roles/netbird/defaults/main.yml:
- odebrano netbird_run_as_system_service (nepotreba)
- pridana poznamka o instalaci

playbook priprav-novy-server.yml:
- hlavicka: 'NetBird (mesh VPN klient - apt balicek, NE Docker)'

group_vars/all.yml.example:
- pridana dokumentace https://docs.netbird.io/get-started/install
- komentare rikaji, ze to neni Docker sluzba

README.md:
- tabulka roli: 'apt balicek, ne Docker'
- krok 8: 'NetBird (mesh VPN klient - apt balicek)'

Postup instalace:
- Linux server: ansible role -> apt install netbird
- macOS workstation: brew install --cask netbird (v Brewfile)
- Windows: instalator z netbird.io
- Registrace: netbird up --setup-key <key> (z app.netbird.io)

playbooks/priprav-novy-server.yml

@@ -9,7 +9,7 @@
 # 5. Docker Engine + Compose plugin
 # 6. Uzivatel deploy v docker group (docker bez sudo)
 # 7. Adresarova struktura (/home/deploy/{docker,scripts,backups,logs,...})
-# 8. NetBird (mesh VPN - klient + setup key)
+# 8. NetBird (mesh VPN klient - apt balicek, NE Docker)
 # 9. fail2ban (SSH jail)
 #
 # Poznamka: firewall (UFW) se nenastavuje - podle pozadavku uzivatele.
@@ -113,7 +113,7 @@
 
           SSH pristup: deploy@{{ ansible_host | default(inventory_hostname) }}:{{ ssh_port }}
           Docker: docker --version (bez sudo)
-          NetBird: netbird status (mesh VPN)
+          NetBird: netbird status (mesh VPN klient, ne Docker)
           Sluzby: /home/{{ deploy_user }}/docker/<sluzba>/
 
           Dalsi kroky: