refactor: improve project structure, idempotency, and security

- Replace interactive python setup script with native Ansible vars_prompt.

- Add missing Prometheus helm values template for resource management on Raspberry Pi.

- Replace deprecated apt_key module usage with modern keyring file download.

- Add project files: requirements.txt, requirements.yml, and .gitignore.

.gitignore

@@ -0,0 +1,12 @@
+# Ansible dynamic content
+inventory.ini
+*.retry
+
+# Python Virtual Environment and cache
+venv/
+.venv/
+__pycache__/
+*.py[cod]
+
+# Ansible local folders
+.ansible/