fix(cdn): purge the staging zone too

cran-rpkgs-test was added as a second pull zone on the same B2 origin but
never added to the purge list, so it kept serving pre-reindex indexes
behind the same ~370 day cache_expiration_time as production.

That is not cosmetic: a verification run against staging measures whatever
the edge still holds. amd64/alpine323 reported 161 regressions there while
production, freshly purged, reported zero for the same objects. The
staging zone exists to be measured, so it has to be purged like any other.

.crow/reindex.yaml

@@ -172,7 +172,12 @@ steps:
         from_secret: BUNNYNET_API_KEY
       # cran.rpkgs.com and cran.allianceswisspass.devxy.io are on separate
       # Bunny pull zones, so both must be purged after the shared origin changes.
-      BUNNY_PULLZONES: '3857050 cran.allianceswisspass.devxy.io'
+      # The staging zone is listed too. It shares the B2 origin, so an index
+      # it still holds is a stale copy of the same object, and its
+      # cache_expiration_time is the same ~370 days: without a purge here it
+      # serves pre-reindex indexes indefinitely and any verification run
+      # against it measures the past.
+      BUNNY_PULLZONES: '3857050 cran.allianceswisspass.devxy.io cran-rpkgs-test.b-cdn.net'
     commands:
       - apk add --no-cache -q bash curl jq
       # Crow carries the checkout from the re-index step into this step.

.crow/weekly-rebuild-reindex.yaml

@@ -175,7 +175,12 @@ steps:
         from_secret: BUNNYNET_API_KEY
       # cran.rpkgs.com and cran.allianceswisspass.devxy.io are on separate
       # Bunny pull zones, so both must be purged after the shared origin changes.
-      BUNNY_PULLZONES: '3857050 cran.allianceswisspass.devxy.io'
+      # The staging zone is listed too. It shares the B2 origin, so an index
+      # it still holds is a stale copy of the same object, and its
+      # cache_expiration_time is the same ~370 days: without a purge here it
+      # serves pre-reindex indexes indefinitely and any verification run
+      # against it measures the past.
+      BUNNY_PULLZONES: '3857050 cran.allianceswisspass.devxy.io cran-rpkgs-test.b-cdn.net'
     commands:
       - apk add --no-cache -q bash curl jq
       # Crow carries the checkout from the re-index step into this step.