Add recipe generator for automation and DRY recipes

- create generate_recipe.py: CLI tool for generating recipes from templates
- add recipe_templates.yaml: 5 base templates (virtual-desktop, virtual-server, desktop-hypervisor, live-desktop, live-server)
- add recipes_manifest.yaml: 16 recipe variants defined declaratively
- add Makefile: automation targets for generate, validate, test
- add requirements.txt: PyYAML dependency
- add tests/test_recipe_generator.py: 25 pytest tests

This enables:
- Template-based recipe generation with minimal duplication
- One-line variant addition via YAML manifest editing
- Automatic duplicate include prevention
- Ingredient path validation

Generated recipes are committed for reproducibility as per project conventions.

recipes/desktop.cfg

@@ -0,0 +1,23 @@
+#            __          ____                        ____  _____
+#     ____  / /_  __  __/ / /___  ____ ___  ___     / __ \/ ___/
+#    / __ \/ __ \/ / / / / / __ \/ __ `__ \/ _ \   / / / /\__ \
+#   / /_/ / / / / /_/ / / / /_/ / / / / / /  __/  / /_/ /___/ /
+#  / .___/_/ /_/\__, /_/_/\____/_/ /_/ /_/\___/   \____//____/
+# /_/          /____/
+
+# A recipe for a generic desktop hypervisor
+
+%include ../ingredients/core.cfg # Text mode
+%include ../ingredients/core-storage.cfg # ext4-based storage configuration
+%include ../ingredients/core-bootloader-grub.cfg # Set bootloader to GRUB
+%include ../ingredients/core-locale.cfg # System locale set to Swiss French as keyboard layout and English as language
+%include ../ingredients/core-security-on.cfg # Lock root account, enable firewall and SELinux
+%include ../ingredients/core-services.cfg # Required systemd services
+%include ../ingredients/core-network.cfg # Network configuration
+%include ../ingredients/core-packages-mandatory.cfg # Mandatory packages 
+%include ../ingredients/core-packages-default.cfg # Default but not necessary packages
+%include ../ingredients/core-packages-hardware-support.cfg # Extended hardware support 
+%include ../ingredients/core-fedora-repo-rawhide.cfg # Official repositories for Fedora Rawhide
+%include ../ingredients/core-post.cfg # Triggered after the installation
+%include ../ingredients/core-initial-setup-desktop.cfg # OEM setup for GNOME Shell
+%include ../ingredients/base-desktop-gnome.cfg # A GNOME Shell-based desktop environment