fix(bikeshare): scope city failures to range and report partial outages

A failure now ends when its city leaves range or the camera rises above the
activation gate, so an empty map no longer reads LOAD FAILED. Late activation
and status rejections are ignored like late successes. Partial failure reads
DEGRADED, every in-range city failing over cached points reads STALE, and
freshness advances only on a refresh that succeeded. Behavioural tests drive
the real proximity, update and enable paths. Docs say no licence is published
for Toronto and list Social Bicycles and PBSC. The merge also restored the #61
GBFS v3 changelog entry that an earlier merge on main dropped.

CHANGELOG.md

@@ -5,14 +5,19 @@
   flag that only a successful *activation* cleared — and an already-loaded city
   never activates again. A dead feed re-entering camera range therefore latched
   LOAD FAILED permanently over a map still drawing every other city's stations.
-  Failure is now tracked per city and reported only when it leaves the layer
-  with nothing to draw; a city that recovers clears its own failure.
+  Failure is now tracked per city: a city that fails beside others still
+  drawing marks the layer DEGRADED, polls that all fail over previously drawn
+  points read STALE without advancing freshness, and LOAD FAILED is reported
+  only when nothing is left to draw. A city that recovers clears its own
+  failure, a failure is dropped once its city leaves range or the camera rises
+  above the activation altitude, and late results from superseded requests are
+  ignored.
 
   Repointed the three feeds whose operators had moved: Reddy Bikeshare (Buffalo)
   to Social Bicycles, Tugo (Tucson) and Trinity Metro (Fort Worth) to PBSC.
   Dropped CoGo (Columbus) and Broward B-cycle (Fort Lauderdale), whose systems
   have wound down — CoGo's feed reports no stations and last moved a bike in
-  March 2025. All 31 remaining systems were verified live.
+  March 2025. The three repointed feeds were verified live.
 
 - Add Bike Share Toronto (1,069 stations) to the bikeshare registry. The system
   publishes the same PBSC GBFS v2 feeds as the Austin, Honolulu and Chattanooga