feat: VERBOSE=true enables DEBUG-level console output

The log file already captures DEBUG unconditionally. This env var wires
the same to the Rich console handler for troubleshooting without needing
to read the log file.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

winnow/cli.py

@@ -20,7 +20,8 @@ logger = logging.getLogger(__name__)
 def main() -> None:
     """Entry point for winnow CLI."""
     try:
-        setup_logging(verbose=False)
+        verbose = os.environ.get("VERBOSE", "").lower() in ("true", "1", "yes")
+        setup_logging(verbose=verbose)
 
         console.print(r"""
     [bold blue]winnow[/bold blue]