Cleanup NUL Files

Find and remove nul files that are accidentally created by some tools (like Claude Code) on Windows.

Background

On Windows, nul is a reserved device name (like /dev/null on Unix). Some tools may accidentally create actual files named nul, which can cause issues. This skill helps locate and remove them.

Strict Execution Flow

Do NOT use any scripts. Do NOT skip or merge phases. Execute each phase in order.

Phase 1: Environment Detection (MANDATORY — must display results before proceeding)

Detect and explicitly display the following before doing anything else: