v1.2.0: an explainer made from one prompt

Added

• examples/dns-resolution: an explainer the skill made from one prompt, unedited, with a live demo.

Changed

• The contact sheet (motion shot with no step) shows each step's full narration instead of cutting it at three lines.

Fixed

• motion shot f.html 99 silently showed the last step; out-of-range steps now fail with the valid range.
• Shot paths no longer contain // when TMPDIR ends in a slash.