feat: patch registry + wiring for per-package patching (#103)

## Summary

Adds the curated **patch registry** and wiring that drives bincraft's new package-patching mechanism (see bincraft PR `feat/package-patching`).
Lets specific packages be patched (env/configure/Makevars overrides or source diffs) before pak installs them — including as transitive dependencies — so compiler-/OS-specific failures like RcppParallel's bundled TBB stop cascading.

## What's included

- `local/patches/registry.json` — initial entry: RcppParallel with `RCPP_PARALLEL_USE_TBB=0` for alpine / ubuntu-2604, plus `local/patches/README.md` schema docs.
- `local/validate-patches.R` — validates schema, referenced patch files, and ambiguous overlaps; clean failure + exit 1 (no stacktrace).
- `.pre-commit-config.yaml` — a `validate-patches` hook (re-runs when the registry or the validator changes).
- `local/build-one.R` / `local/build-all.R` — pass `patches = "local/patches"` to `bincraft::build_binary_package()`.
- `specs/2026-06-30-package-patching-design.md` and `plans/2026-06-30-package-patching-implementation.md`.

## ⚠️ Merge ordering (blocker)

This PR adds a `patches = ...` argument to `build_binary_package()` calls.
The `.crow/*.yaml` workflows currently pin bincraft **v4.2.3**, which does not accept that argument — CI will error with `unused argument (patches=...)` until:

1. bincraft **v4.3.0** is released (PR `feat/package-patching`), and
2. the pin is bumped in `.crow/build-all-versions-install-deps.yaml`, `.crow/build-all-versions.yaml`, and `.crow/process-updates.yaml`.

The `.crow` pin bump will be added to this PR once bincraft v4.3.0 is tagged. Do not merge before then.

Reviewed-on: #103

.crow/build-all-versions.yaml

@@ -121,7 +121,7 @@ steps:
       # to a zero-length value and breaks every metadata query and the sysdeps
       # install). Pin bincraft here, exactly like the R-minor pass below.
       - rm -rf /mnt/cache/R-pkgs/00LOCK-*
-      - /opt/R/$R_VERSION/bin/R -q -e 'if (!requireNamespace("bincraft", quietly = TRUE) || packageVersion("bincraft") != "4.2.3") pak::pak("git::https://codefloe.com/rpkgs/bincraft.git@v4.2.3")'
+      - /opt/R/$R_VERSION/bin/R -q -e 'if (!requireNamespace("bincraft", quietly = TRUE) || packageVersion("bincraft") != "4.3.1") pak::pak("git::https://codefloe.com/rpkgs/bincraft.git@v4.3.1")'
       - 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
       - |
@@ -133,7 +133,7 @@ steps:
           echo "=== R-minor-sensitive pass under R $RV ==="
           LIB="/mnt/cache/R-pkgs-$RMINOR"
           mkdir -p "$LIB"
-          R_LIBS_USER="$LIB" "$(dirname "$RBIN")/R" -q -e 'if (!requireNamespace("bincraft", quietly = TRUE) || packageVersion("bincraft") != "4.2.3") pak::pak("git::https://codefloe.com/rpkgs/bincraft.git@v4.2.3")' || true
+          R_LIBS_USER="$LIB" "$(dirname "$RBIN")/R" -q -e 'if (!requireNamespace("bincraft", quietly = TRUE) || packageVersion("bincraft") != "4.3.1") pak::pak("git::https://codefloe.com/rpkgs/bincraft.git@v4.3.1")' || true
           R_LIBS_USER="$LIB" $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; first arg is the codename (e.g. "alpine324"),