Clean up inventory, group_vars, and prefill READMEs

- hosts.ini: underscore group names, hostname aliases with ansible_host
- move ansible_user/ansible_port to group_vars/all.yml
- rename group_vars files to match underscore group names
- trim sftp group_vars to its only override (password auth off)
- run.yml: load moved secrets file (group_vars/secrets.yml)
- untrack .DS_Store, extend .gitignore
- prefill root/ansible/server READMEs, add jira + cloud server folders
- update CLAUDE.md to match

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

ansible/hosts.ini

@@ -1,15 +1,14 @@
-[phy-z-srv-jira]
-192.168.66.41 ansible_user=sbxadmin ansible_port=22
+[phy_z_srv_jira]
+phy-z-srv-jira ansible_host=192.168.66.41
 
-[phy-z-srv-cloud]
-192.168.66.66 ansible_user=sbxadmin ansible_port=22
+[phy_z_srv_cloud]
+phy-z-srv-cloud ansible_host=192.168.66.66
 
-[phy-z-srv-git]
-192.168.66.67 ansible_user=sbxadmin ansible_port=22
+[phy_z_srv_git]
+phy-z-srv-git ansible_host=192.168.66.67
 
-[phy-z-dmz-sftp01]
-192.168.66.68 ansible_user=sbxadmin ansible_port=22
-
-[phy-z-srv-gpu01]
-192.168.66.69 ansible_user=sbxadmin ansible_port=22
+[phy_z_dmz_sftp01]
+phy-z-dmz-sftp01 ansible_host=192.168.66.68
 
+[phy_z_srv_gpu01]
+phy-z-srv-gpu01 ansible_host=192.168.66.69