Merge branch 'main' into feat/voice-geometry

Picks up the terrain partial-heights work (#1456). No conflicts; it changes
no voice prompt or tool description.

changelog.d/1456-terrain-partial-heights.md

@@ -0,0 +1,3 @@
+- A terrain request the proxy can only partly answer (a 429 pause, or a point
+  the upstream returns without a height) now keeps the real heights it has
+  instead of putting the whole chunk on the geoid (quanticsoul4772, #1456).