feat: R-minor-sensitive binary builds (full + iterative) (#84)

## Summary

Builds R-minor-sensitive CRAN packages once per installed R minor version (into per-minor S3 slots `…/contrib/<x.y>/`) and everything else once into the generic slot, driven by bincraft 4.2.0's ABI classifier. Both the full and iterative pipelines are covered.

## What's in here

**Detection / precompute**

- `local/r-minor-helpers.R` — pure `classify_from_metadata()` (NeedsCompilation / risky `LinkingTo`) + `parse_build_args()`, with unit tests.
- `local/packages-to-build.R` — adds a per-package `r_minor_sensitive` flag: cheap CRAN-metadata rules first, source download + `bincraft::needs_per_minor_recompile()` only for the ambiguous compiled subset (fail-safe to sensitive). Classified once per package, applied to all versions.

**Full build**

- `local/build-all.R` — passes the per-row `is_r_minor_sensitive` flag; new `--sensitive-only` mode builds just the risky subset.
- `.crow/build-all-versions-{amd64,arm64}.yaml` — install-deps persists the sensitive subset; build step runs a sensitive-only pass under each non-primary `/opt/R/*` minor; new step uploads the generic index plus a per-minor index for each minor.

**Iterative build**

- All 14 `.crow/process-updates-*.yaml` — primary pass uses `r_minor_detection = 'classifier'`; a sensitive-only multi-R pass builds risky updates under each other minor; per-minor index upload added.

**Tooling / housekeeping**

- Pins bincraft `v4.1.1` → `v4.2.0` across all workflows; removes the superseded standalone `build-r-minor-sensitive-packages.yaml`.
- Adds prek/pre-commit hooks (prettier, markdownlint, editorconfig-checker, yamllint, air) and applies them repo-wide; excludes the verbatim GPL `LICENSE.md` and auxiliary shell scripts.
- Design + implementation docs under `docs/superpowers/`.

## Requires before merge

- A `v4.2.0` git tag must be pushed on the bincraft repo (codefloe.com/rpkgs/bincraft) — the workflow install steps pin `@v4.2.0`. The full-build install-deps clones `main`, so it is unaffected.

Reviewed-on: #84

.crow/build-all-versions-amd64.yaml

@@ -39,7 +39,7 @@ depends_on:
 
 steps:
   - name: 'Build binaries'
-    image: "reg.devxy.io/rpkgs/build-env-${OS}:${OS_VERSION}"
+    image: 'reg.devxy.io/rpkgs/build-env-${OS}:${OS_VERSION}'
     pull: true
     environment:
       RED_HAT_DEV_PW:
@@ -57,7 +57,7 @@ steps:
       # normal env vars
       GIT_USER: pat-s
       # set the location of the 'pkgcache' cache dir which persists the R package dependencies needed to install the packages themselves
-      R_PKG_CACHE_DIR: ""
+      R_PKG_CACHE_DIR: ''
       R_LIBS_USER: /mnt/cache/R-pkgs
       CCACHE_DIR: /mnt/cache/ccache
       NCPUS: 2
@@ -70,6 +70,15 @@ steps:
       # pkgs = readRDS('/mnt/cache/pkgs_amd64.rds');
       - XVFB=$(command -v xwfb-run 2>/dev/null || command -v xvfb-run); XVFB_ARGS=""; if command -v xwfb-run >/dev/null 2>&1; then dnf install -y -q weston 2>/dev/null; XVFB_ARGS="-c weston"; fi
       - $XVFB $XVFB_ARGS -n $SPLIT_INDEX -- /opt/R/$R_VERSION/bin/Rscript local/build-all.R $SPLIT_INTO $SPLIT_INDEX $NCPUS 2>&1
+      - |
+        PRIMARY_MINOR=$(echo "$R_VERSION" | cut -d. -f1-2)
+        for RBIN in /opt/R/*/bin/R; do
+          RV=$(basename "$(dirname "$(dirname "$RBIN")")")
+          RMINOR=$(echo "$RV" | cut -d. -f1-2)
+          [ "$RMINOR" = "$PRIMARY_MINOR" ] && continue
+          echo "=== R-minor-sensitive pass under R $RV ==="
+          $XVFB $XVFB_ARGS -n $SPLIT_INDEX -- "$(dirname "$RBIN")/Rscript" local/build-all.R --sensitive-only $SPLIT_INTO $SPLIT_INDEX $NCPUS 2>&1 || true
+        done
       # archive missed packages
       - /opt/R/$R_VERSION/bin/R -q -e "bincraft::process_unarchived_pkgs(paste(Sys.getenv('OS'), Sys.getenv('OS_VERSION')), Sys.getenv('ARCH'), workers = $NCPUS)"
     backend_options:
@@ -97,3 +106,47 @@ steps:
             operator: 'Equal'
             value: 'true'
             effect: 'NoSchedule'
+  - name: 'Upload package indexes'
+    image: 'reg.devxy.io/rpkgs/build-env-${OS}:${OS_VERSION}'
+    pull: true
+    environment:
+      B2_S3_ACCESS_KEY:
+        from_secret: B2_S3_ACCESS_KEY
+      B2_S3_SECRET_KEY:
+        from_secret: B2_S3_SECRET_KEY
+      R_LIBS_USER: /mnt/cache/R-pkgs
+    volumes:
+      - ${ARCH}-binaries-r-dep-cache-${OS}-${OS_VERSION//./}:/mnt/cache
+    commands:
+      - |
+        CODENAME=$(/opt/R/$R_VERSION/bin/Rscript -e "cat(bincraft::set_codename(NULL))")
+        /opt/R/$R_VERSION/bin/R -q -e "bincraft::upload_package_index(codename = '$CODENAME', s3_endpoint = 'https://s3.eu-central-003.backblazeb2.com', s3_region = 'eu-central-003', s3_bucket = 'devxy-rpkgs-binaries', s3_access_key_id = Sys.getenv('B2_S3_ACCESS_KEY'), s3_secret_access_key = Sys.getenv('B2_S3_SECRET_KEY'))"
+        for RBIN in /opt/R/*/bin/R; do
+          RMINOR=$(basename "$(dirname "$(dirname "$RBIN")")" | cut -d. -f1-2)
+          /opt/R/$R_VERSION/bin/R -q -e "bincraft::upload_package_index(codename = '$CODENAME', r_minor = '$RMINOR', s3_endpoint = 'https://s3.eu-central-003.backblazeb2.com', s3_region = 'eu-central-003', s3_bucket = 'devxy-rpkgs-binaries', s3_access_key_id = Sys.getenv('B2_S3_ACCESS_KEY'), s3_secret_access_key = Sys.getenv('B2_S3_SECRET_KEY'))" || true
+        done
+    backend_options:
+      docker:
+        resources:
+          requests:
+            memory: 5Gi
+            cpu: 1000m
+          limits:
+            memory: 20Gi
+            cpu: 2000m
+      kubernetes:
+        resources:
+          requests:
+            memory: 5Gi
+            cpu: 1000m
+          limits:
+            memory: 20Gi
+            cpu: 2000m
+        nodeSelector:
+          kubernetes.io/arch: ${ARCH}
+          node.kubernetes.io/instance-type: ${K8S_INSTANCE_TYPE}
+        tolerations:
+          - key: 'CI'
+            operator: 'Equal'
+            value: 'true'
+            effect: 'NoSchedule'