docs: add scope and HUD changelog entry

changelog.d/1397-scope-controls-hud-readability.md

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+- Add a Scope checkbox and extend feathering to 200%, retaining scope settings
+  across HUD layouts, share links and scenes. Give Tactical, Operator and Minimal
+  text subtle black backings, including vertical metadata, while keeping map
+  attribution clear (bilawalsidhu, #1397).