refactor(ci): use multi-R-version images in weekly-audit-missing workflows

Drop the R-version suffix from each image tag, add an explicit
R_VERSION env var per file, and invoke R via
/opt/R/${R_VERSION}/bin/R at every call site.

Also fixes the alpine-322 audit image, which was previously pointing
at alpine:3.23 instead of alpine:3.22. The alpine-321 audits stay on
alpine:3.23 since no 3.21 image exists in the new scheme — they only
query S3/CRAN, so the container OS does not affect correctness.

.crow/weekly-audit-missing-redhat-9-arm64.yaml

@@ -8,7 +8,7 @@ skip_clone: true
 
 steps:
   - name: 'Audit missing binaries'
-    image: reg.devxy.io/rpkgs/build-env-redhat:9-4.4.3
+    image: reg.devxy.io/rpkgs/build-env-redhat:9
     pull: true
     environment:
       B2_S3_ACCESS_KEY:
@@ -27,12 +27,13 @@ steps:
       PLATFORM: redhat-9
       ARCH: arm64
       R_LIBS_USER: /mnt/cache/R-pkgs
+      R_VERSION: 4.4.3
     commands:
       - git clone -q https://pat-s:$$REPO_RO_TOKEN@git.devxy.io/devxy/build-cran-binaries.git .
       - mkdir -p /mnt/cache/packages /mnt/cache/R-pkgs
       - rm -rf /mnt/cache/R-pkgs/00LOCK-*
-      - R -q -e 'pak::pak(c("git::https://codefloe.com/rpkgs/bincraft.git", "httr2", "jsonlite"))'
-      - R -q -e 'source("local/weekly-missing-binaries-audit.R")'
+      - /opt/R/${R_VERSION}/bin/R -q -e 'pak::pak(c("git::https://codefloe.com/rpkgs/bincraft.git", "httr2", "jsonlite"))'
+      - /opt/R/${R_VERSION}/bin/R -q -e 'source("local/weekly-missing-binaries-audit.R")'
     backend_options:
       kubernetes:
         resources: