fix(hud): drop a summary reply once the camera starts moving (#1384)

Discard stale HUD summaries when camera movement starts and allow cancelled requests to retry for unchanged place context.

Contribution by @quanticsoul4772.

changelog.d/1384-hud-summary-moving.md

@@ -0,0 +1,4 @@
+- The HUD's AI place summary drops a reply that arrives after the camera has
+  started moving, so a summary asked for before a flight no longer names the
+  old place mid-flight. Cancelled or partially typed summaries retry even if the place
+  context stays the same (quanticsoul4772, #1384).