feat(stats): collect CDN access logs and publish download statistics

Add an hourly download-stats pipeline that reads the cran-rpkgs Bunny
access logs into a download_stats schema in the build metadata database
and publishes aggregated counts to /stats/downloads.json for the
rpkgs.com /stats page.

- Classify each request (download, index, redirect reason, probe, noise)
  mirroring the edge router, and split cloud/CI networks from the rest.
- De-duplicate downloads per client, package version and day, and key
  clients on a salted HMAC so no IP is stored or published.
- Exclude our own CI runners and record run windows to show gaps.
- Declare the zone's logging settings and allow CORS for JSON.

local/archive-missed-pkgs.R

@@ -8,8 +8,8 @@ s3fs::s3_file_system(
   refresh = T
 )
 
-arch = "arm64"
-os = "alpine321"
+arch <- "arm64"
+os <- "alpine321"
 
 files <- s3fs::s3_dir_ls(sprintf(
   "devxy-r-package-binaries-hel1/%s/%s/latest/src/contrib",
@@ -17,11 +17,11 @@ files <- s3fs::s3_dir_ls(sprintf(
   os
 ))
 length(unique(sapply(strsplit(basename(files), "_"), function(x) x[1])))
-non_archived = unique(sapply(strsplit(basename(files), "_"), function(x) {
+non_archived <- unique(sapply(strsplit(basename(files), "_"), function(x) {
   x[1]
 })[duplicated(sapply(strsplit(basename(files), "_"), function(x) x[1]))])
 # RInno is not built because it only exists for Windows
-non_archived = setdiff(non_archived, "RInno")
+non_archived <- setdiff(non_archived, "RInno")
 # future::plan("sequential", workers = 8)
 future::plan("sequential", workers = 1)
 # future.apply::future_lapply(non_archived, function(x) archive_package(x, codename = os, arch = arch))