fix(bikeshare): preserve unknown availability counts

docs/CURRENT-STATE.md

@@ -1275,6 +1275,9 @@ and stale/error responses remain unchanged. Each has a Node-only package entry
 under `gods-eye-view/server/providers/`. Portable terrain mechanics, traffic tile
 math and GBFS source rules are available under `gods-eye-view/sources/`.
 The browser layers and their rendering remain in their existing modules.
+GBFS null or empty availability counts retain an unknown value through station
+parsing and rendering; they use the neutral station color rather than reporting
+an empty dock. Explicit zero and caller-supplied numeric fallbacks remain valid.
 
 ## Terrain height cache bound