Month-End Close Flux Commentator

Generate account-level flux (period-over-period) commentary for the month-end close process. For every GL account exceeding a materiality threshold (absolute dollar, % change, or both), the skill identifies the drivers of the change, proposes the narrative explanation a controller would write, and flags items requiring further investigation or a journal-entry adjustment. Complementary to `budget-variance-analyzer.md`, which examines plan vs. actual at a summary level; this skill examines period-over-period change at the GL-account level with the narrative output that feeds the close file, MD&A footnotes, and the CFO review deck.