Capture session state at end of a coding session so a future Claude Code session can resume cold, or resume from a prior handoff. Trigger PROACTIVELY when the user signals end of session — "wrapping up", "call it for tonight", "let's stop here", "I need to go", "continue tomorrow", "pick this up later", "save where we are", "done for now" — and also on explicit /handoff. For resume, trigger when user says "resume", "pick up where we left off", "continue from yesterday", "what was I working on", or /handoff resume.
