Track the six-part catalog-completion plan in git

Supersedes the plan-mode scratch file (~/.claude/plans/, session-local)
after a mid-session rate-limit interruption required reconstructing plan
state from the conversation transcript. The lesson driving this commit:
the plan lives in git, not in a scratch file, so a future interruption
can recover from git log/git status alone.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_016i9S7LQsCL3FGaih3ZTRBJ

Author: WilfordGrimley