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.

scripts/Makefile

@@ -0,0 +1,30 @@
+.PHONY: help generate-recipes validate-recipes test clean install-deps
+
+help:
+	@echo "Phyllome OS Recipe Generator"
+	@echo ""
+	@echo "Available targets:"
+	@echo "  generate-recipes  - Generate all recipes from manifest"
+	@echo "  validate-recipes  - Validate existing recipes"
+	@echo "  test              - Run pytest test suite"
+	@echo "  clean             - Remove generated recipes"
+	@echo "  install-deps      - Install Python dependencies"
+
+install-deps:
+	pip install -r requirements.txt
+
+generate-recipes:
+	python generate_recipe.py \
+		--manifest recipes_manifest.yaml \
+		--output-dir ../recipes/
+
+validate-recipes:
+	python generate_recipe.py \
+		--validate ../recipes/*.cfg
+
+test:
+	pytest ../tests/test_recipe_generator.py -v
+
+clean:
+	rm -f ../recipes/*.cfg
+	@echo "Generated recipes removed. Edit recipes_manifest.yaml and run 'make generate-recipes' to regenerate."