heditor 1.2.0: no dead air — trim block-edge silence, tighter internal pauses, heditor gaps gate and test

• No dead air: prepare_cut now trims the silence at the edges of every block (lead=0.08, tail=0.12 s around the first/last voiced window) and shortens internal pauses longer than 0.35 s (edge=0.12). Block boundaries snap to the quietest point of their radius, so junctions used to keep silence from both sides (0.8–1.3 s gaps that read as uncut pauses). lead=None/tail=None restore the old behaviour.
• New heditor gaps <work> [max_s]: lists every silence left in the assembled voice (junction or internal, with surrounding words) and fails above 0.45 s. heditor test gained test_no_dead_air; the gate is in quality-gates.md and workflow.md.