closure-log-aggregation

Use when running /close-epic, when about to file the epic closure comment, when an operator asks "what did we consider but not pursue in this epic", or when about to summarize an epic's surfaced-but-deferred work. Also use when about to grep sub-ticket comments for closure-log entries by hand, when about to skip a ### Considered but not pursued section because it "looks like" the duplicate of another, when h2 vs h3 heading drift would otherwise drop entries silently, or when about to omit closure-log content from the epic closure because none was found at the wrong heading level.