ci: fix environment config validation workflow

Use 'uv run python' instead of bare 'python' to access virtual environment dependencies.
The workflow installs pyyaml and pydantic with uv but was running validation script
outside the virtual environment, causing ModuleNotFoundError.

Author: alex-feel

.github/workflows/validate-configs.yml

@@ -67,10 +67,10 @@ jobs:
               # Check if it's a template or library config
               if [[ "$config_file" == *"templates/"* ]]; then
                 echo "Note: Template file - allowing placeholder values"
-                python scripts/validate_environment_config.py "$config_file" || true
+                uv run python scripts/validate_environment_config.py "$config_file" || true
               else
                 # Library configs must pass strict validation
-                if ! python scripts/validate_environment_config.py "$config_file" --strict; then
+                if ! uv run python scripts/validate_environment_config.py "$config_file" --strict; then
                   exit_code=1
                 fi
               fi