OpenScrub v1.0.14

OpenScrub v1.0.14

This release removes the two biggest "you should have tuned a knob"
excuses from the scanning engine.

• Deep backtrack — when something (a face, a name, a plate) turns out
to have been on screen longer than the backtrack buffer reaches,
OpenScrub no longer asks you to raise a setting. It now goes back to
the video file itself and searches — as far back as it needs to —
until it finds the true first frame, and starts the blur there.
Coverage of an object's first appearance no longer depends on any
window size.

• Self-tuning scan pacing — the scan interval now adapts to your
footage: it relaxes while the screen is static, tightens when a lot
is changing, and scans sooner during fast scrolling. Fixed pacing is
still available with --adaptive off. All safety guarantees are
unchanged: content that scrolls in unscanned is covered by safety
bands until it has been read.

Both are on by default. No settings to learn, nothing to configure.

Full test suite green (16 end-to-end tests, including a new one proving
the deep backtrack finds an onset beyond the buffer without
over-extending before the object existed).