v0.3.0

• plate render --html out.html: write the page's DOM once its scripts have settled, a static copy with every script's work done. No --size needed. Refuses (exit 1, file removed) a dump that does not end in </html> or that contains a --fail-if string; Chrome's non-zero teardown exit is ignored when the page is complete.
• Engine: Cmd.AllowExit lets a caller judge an engine's output by content rather than exit status.
• Output-collision check now covers every pair of --png, --pdf, --html.