Enforce uppercase README.md and TODO.md filenames

- Renamed all Readme.md → README.md
- Renamed all Todo.md → TODO.md
- Added integration test (tests/integration/test_filename_conventions.py) to automatically check naming convention.

Background:
Consistency in file naming (uppercase README.md and TODO.md) avoids issues with case-sensitive filesystems and ensures desktop cards (e.g. Pretix) are properly included.
Ref: https://chatgpt.com/share/68b1d135-c688-800f-9441-46a3cbfee175

docs/guides/administrator/README.md

@@ -0,0 +1,22 @@
+# Administrator Guide
+
+This guide is for **system administrators** who are deploying and managing Infinito.Nexus infrastructure.
+
+## Setting Up Infinito.Nexus 🏗️
+Follow these guides to install and configure Infinito.Nexus:
+- [Setup Guide](SETUP_GUIDE.md)
+- [Configuration Guide](CONFIGURATION.md)
+- [Deployment Guide](DEPLOY.md)
+
+## Key Responsibilities 🔧
+- **User Management** - Configure LDAP, Keycloak, and user permissions.
+- **Security & Backups** - Set up `sys-bkp-rmt-2-loc`, `svc-bkp-loc-2-usb`, and `core-security` roles.
+- **Application Hosting** - Deploy services like `Nextcloud`, `Matrix`, `Gitea`, and more.
+- **Networking & VPN** - Configure `WireGuard`, `OpenVPN`, and `Nginx Reverse Proxy`.
+
+## Managing & Updating Infinito.Nexus 🔄
+- Regularly update services using `update-docker`, `update-pacman`, or `update-apt`.
+- Monitor system health with `sys-ctl-hlth-btrfs`, `sys-ctl-hlth-webserver`, and `sys-ctl-hlth-docker-container`.
+- Automate system maintenance with `sys-lock`, `sys-ctl-cln-bkps`, and `sys-ctl-rpr-docker-hard`.
+
+For more details, refer to the specific guides above.