Generates a categorized work summary from GitHub activity (PRs authored, issues created, code committed) for a given time period and organization, using parallel subagents for fast detail fetching. Use when the user asks "what did I work on", "what did I do last week", wants a work log, weekly update, standup notes, sprint recap, accomplishments list, performance review input, or any summary of their contributions. DO NOT TRIGGER for repository changelogs, release notes, or team-wide activity reports.