Consolidate clamped its range to the track's last clip end plus one
second, so on an empty track a 0-5 s selection made a 1 s clip and a
2-7 s selection made nothing. It now renders, clears and places exactly
the selection, and refuses a selection too long to render instead of
placing a shorter clip. Prepare DPE keeps the old per-track bound.
Fixes#164
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
