docs(changelog): add the #1719 fragment

Co-Authored-By: Claude Fable 5.2 <[email protected]>

changelog.d/1719-detection-overlay-paint.md

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+- The detection overlay no longer rebuilds every bracket on a paint where the
+  view and every contact are unchanged, which cuts frame work by a fifth to a
+  third at a whole-globe view of Live Flights with a still camera (mazy1998,
+  #1719).