fix: resolve CI linting and type errors

src/promptforge/cli/main.py

@@ -1,4 +1,5 @@
-import sys
+"""Main CLI entry point."""
+
 import click
 from pathlib import Path
 
@@ -20,4 +21,4 @@ def main(ctx: click.Context, prompts_dir: Path):
 
 
 if __name__ == "__main__":
-    main()
+    main()