Agent Skills: devlog

Keep DEVLOG.md up to date and use it to resume project context in the user's personal developer-log style. Use when the user asks to update, write, continue, summarize, resume, catch up from, or maintain @DEVLOG.md / DEVLOG.md after or before a work session, or asks to capture what they did, learned, decided, got stuck on, where to continue next, or what happened last time.