Add hostname play and hellsos SSH keys to initial_setup

Adds an opt-in (tags: never,hostname) play that sets the system
hostname to inventory_hostname, and fills in both real authorized
keys for the hellsos user.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

initial_setup.yml

@@ -17,7 +17,8 @@
         groups: []
         sudo_nopasswd: true
         ssh_keys:
-          - "ssh-ed25519 AAAAC3..."
+          - "ssh-rsa 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 hellsos@hellsos-PC"
+          - "ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIKhfQt1VNQo8EbIog4yjU5VEF3mTyMEC7o1Qe95X4JwG jan@rabcan.cz"
 
       - name: jim
         shell: /bin/bash
@@ -109,3 +110,18 @@
                   ['RedHat','Rocky','AlmaLinux','Fedora','OracleLinux','Suse']
                   else 'ssh' }}"
         state: restarted
+
+# ==============================
+# THIRD PLAY: HOSTNAME
+# ==============================
+
+- name: Set hostname from inventory
+  hosts: all
+  become: true
+  tags: never,hostname
+
+  tasks:
+
+    - name: Set system hostname to inventory_hostname
+      ansible.builtin.hostname:
+        name: "{{ inventory_hostname }}"