## Motivation
`cran-rpkgs-test` was added as a second pull zone on the same B2 origin, but it was never added to `BUNNY_PULLZONES`. It therefore keeps serving pre-reindex indexes behind the same ~370 day `cache_expiration_time` as production, and nothing ever refreshes it.
That is not cosmetic. The zone exists to be measured, and a verification run against it measures whatever the edge still holds:
```
production: regressions=0 AGHmatrix Path=NA Built=R 4.5.3; x86_64-pc
staging : regressions=161 AGHmatrix Path=4.5 Built=(none)
```
Same objects, same origin, 161 phantom regressions. I chased that number through two wrong diagnoses before noticing production and staging disagreed.
## Change
Add `cran-rpkgs-test.b-cdn.net` to the purge list in both reindex pipelines.
## Note
A `Cache-Control: no-cache` request header is not a substitute. It was added to the verification script and did **not** clear this: bunny does not honour it for these objects. Purging is the mechanism that works.
Reviewed-on: #181
## Motivation
`weekly-rebuild-reindex` exists to run after `weekly-rebuild-missing`: it declares `depends_on: weekly-rebuild-missing` and is gated on that workflow's `weekly_rebuild_missing` variable. Triggering it manually therefore also starts hours of package rebuilds.
That is the wrong tool when only the index needs regenerating. After rpkgs/bincraft#113 (v5.1.5), which changes how `union_index_records()` decides what a per-minor index steers to, every object in the bucket is already correct and only `PACKAGES*` is stale. Rebuilding to fix an index is pure waste, and the natural cron would take a full cycle to reach every slot.
## Change
Adds `.crow/reindex.yaml`: the index half on its own, manual only, no dependency on a rebuild.
It reuses the same matrix and the same steps as `weekly-rebuild-reindex` — install the latest bincraft release, republish the generic index, loop the installed R versions republishing each per-minor index, purge the edge. No package is built.
Gated on a new `reindex` variable so it cannot be started by the rebuild gate, defaulting to `none` so a manual pipeline creation (which instantiates every file in `.crow/`) matches no matrix row.
```sh
crow pipeline create devxy/build-cran-binaries --var reindex=all
crow pipeline create devxy/build-cran-binaries --var reindex=ubuntu-2404-amd64
```
## Verification
- `crow lint .crow/` passes.
- Gate is manual-only and evaluates `reindex`, with no `depends_on` and no `runs_on` carried over from the rebuild coupling.
Reviewed-on: #177
