## Summary
Fixes the RcppParallel patch, which was a **no-op** and left the build hanging.
The previous registry entry set `env: { RCPP_PARALLEL_USE_TBB: "0" }`. But `RCPP_PARALLEL_USE_TBB` is a **compile-time `-D` flag** in RcppParallel's Makevars — it is never read from the environment. So the override did nothing: `USE_TBB=Linux` (hardcoded from `uname`) still triggered the **bundled Intel TBB build**, which hangs/fails on musl (Alpine) and newer toolchains (g++ 15 on ubuntu-2604). The `Applying patch …` log only meant the env was set, not that it had any effect.
## Fix
Replace the env entry with a **source patch** (`local/patches/RcppParallel/disable-tbb.patch`) on `src/Makevars.in` that, on Linux:
- leaves `USE_TBB` unset → the whole bundled-TBB build/link path is skipped (no hang), and
- forces `PKG_CXXFLAGS += -DRCPP_PARALLEL_USE_TBB=0` → the sources compile the **TinyThread** backend (needed because `RcppParallel.h` otherwise auto-defaults TBB on for glibc Linux).
## Verification
In a Linux container, applying the patch and running `R CMD INSTALL RcppParallel`:
```
bundled_TBB_build=0 # bundled TBB build never runs
* DONE (RcppParallel) # installs via TinyThread
```
## Note
bincraft's `apply_source_patch` shells out to `patch`. If a build-env image lacks the `patch` tool (common on Alpine), the patch will report "did not apply cleanly" and fall back to an unpatched (hanging) build. If that happens, the follow-up is to switch bincraft's patch application to `git apply` (git is always present) — happy to do that if needed.
Reviewed-on: #106
## 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
