feat: pridat netbird roli do priprav-novy-server.yml

Nove role:
- roles/netbird/ - instaluje NetBird mesh VPN klient

Konfigurace:
- netbird_setup_key: '' (placeholder, dopln v group_vars/all.yml)
- netbird_run_as_system_service: true
- netbird_management_url: 'https://api.netbird.io'

Playbook priprav-novy-server.yml:
- pridana role netbird mezi docker a fail2ban
- update hlavicky (krok 8 NetBird)
- update README strom (netbird role)

roles/netbird/defaults/main.yml

@@ -0,0 +1,15 @@
+---
+# Promenne pro netbird roli
+# NetBird - WireGuard-based mesh VPN (https://netbird.io)
+
+# Setup klice pro NetBird registraci
+# Najdes v NetBird dashboardu: https://app.netbird.io/ -> Setup Keys
+# Napr: AAAA-BBBB-CCCC-DDDD-EEEE
+netbird_setup_key: ""
+
+# NetBird spust jako systemova sluzba (root)
+# Pro user-level: netbird up --setup-key XXX (interaktivni)
+netbird_run_as_system_service: true
+
+# Vychozi Management Server (self-hosted nebo oficialni)
+netbird_management_url: "https://api.netbird.io"

roles/netbird/tasks/main.yml

@@ -0,0 +1,46 @@
+---
+- name: Stahnout NetBird GPG klic
+  ansible.builtin.get_url:
+    url: https://pkgs.netbird.io/deb/public.key
+    dest: /etc/apt/keyrings/netbird.asc
+    mode: "0644"
+    force: true
+
+- name: Pridat NetBird repo
+  ansible.builtin.apt_repository:
+    repo: "deb [signed-by=/etc/apt/keyrings/netbird.asc] https://pkgs.netbird.io/deb stable main"
+    filename: netbird
+    state: present
+    update_cache: true
+
+- name: Nainstalovat NetBird
+  ansible.builtin.apt:
+    name:
+      - netbird
+    state: present
+    update_cache: true
+
+- name: Over NetBird verzi
+  ansible.builtin.command: netbird version
+  register: netbird_version_output
+  changed_when: false
+- ansible.builtin.debug:
+    msg: "NetBird nainstalovan: {{ netbird_version_output.stdout }}"
+
+- name: Spust NetBird s setup key (system service)
+  ansible.builtin.command: netbird up --setup-key {{ netbird_setup_key }} --management-url {{ netbird_management_url }}
+  when:
+    - netbird_setup_key | length > 0
+    - netbird_run_as_system_service | bool
+  register: netbird_up_result
+  changed_when: netbird_up_result.rc == 0
+  failed_when: false
+
+- name: Over NetBird stav
+  ansible.builtin.command: netbird status
+  register: netbird_status_output
+  changed_when: false
+  failed_when: false
+- ansible.builtin.debug:
+    msg: "NetBird status: {{ netbird_status_output.stdout }}"
+  when: netbird_setup_key | length > 0