handoff

Write or update a handoff document so the next agent with fresh context can continue this work. Steps: 1. Check if HANDOFF.md already exists in the project 2. If it exists, read it first to understand prior context before updating 3. Create or update the document with: - **Goal**: What we're trying to accomplish - **Current Progress**: What's been done so far - **What Worked**: Approaches that succeeded - **What Didn't Work**: Approaches that failed (so they're not repeated) - **Next Steps**: Clear action items for continuing Save as HANDOFF.md in the project root and tell the user the file path so they can start a fresh conversation with just that path.