feat(build): migrated native pipeline to bazel with remote caching

- Replaced the napi-cli/cargo-zigbuild/cargo-xwin/sccache build path with
  Bazel: rules_rust + crate_universe over Cargo.lock, hermetic zig cc
  toolchains (linux-gnu pinned to glibc 2.17, linux-musl), host Xcode for
  darwin, and a repo-local hermetic clang-cl + llvm-ml + xwin toolchain for
  windows-msvc (bazel/toolchains/msvc).
- All eight shipped addons build as //:natives-<target> via the release
  transition in bazel/defs.bzl (opt, thin LTO, cgu=16, stripped, canonical
  .node naming); scripts/bazel-natives.ts is the single driver for local
  dev and CI.
- Rust validation moved to bazel test + clippy aspects (strict workspace
  policy for opted-in crates, default lints elsewhere, mirroring cargo
  semantics) and the rustfmt aspect; cargo stays as the dev-iteration
  surface, with brush-core/brush-builtins promoted to workspace members
  and excluded from cargo dev tasks to keep their historical scope.
- CI caches through an in-cluster bazel-remote action cache (TLS + basic
  auth, cluster-internal only); GitHub-hosted runners never touch the
  infrastructure and use an actions/cache-backed disk cache instead.
- Deleted the hand-rolled caching machinery: ci-target-cache,
  ci-native-artifact-cache, ci-build-native, native-source-hash,
  find-native-artifacts, restore-linux-native, native-prewarm workflow,
  ensure-* toolchain actions, and all sccache/Swatinem wiring.
- Warm native rebuilds drop from ~20 minutes to seconds; a cold client
  with a warm remote cache rebuilds the linux x64 pair in ~2.5 minutes.

crates/pi-walker/BUILD.bazel

@@ -0,0 +1,39 @@
+load("@crates//:defs.bzl", "aliases", "all_crate_deps")
+load("@rules_rust//rust:defs.bzl", "rust_library", "rust_test")
+
+package(default_visibility = ["//visibility:public"])
+
+exports_files(["Cargo.toml"])
+
+rust_library(
+    name = "pi-walker",
+    srcs = glob(["src/**/*.rs"]),
+    aliases = aliases(),
+    crate_name = "pi_walker",
+    edition = "2024",
+    proc_macro_deps = all_crate_deps(proc_macro = True),
+    version = "17.1.5",
+    deps = all_crate_deps(normal = True),
+)
+
+rust_test(
+    name = "pi-walker_test",
+    crate = ":pi-walker",
+    edition = "2024",
+    proc_macro_deps = all_crate_deps(proc_macro_dev = True),
+    deps = all_crate_deps(normal_dev = True),
+)
+
+[
+    rust_test(
+        name = name + "_test",
+        srcs = ["tests/" + name + ".rs"],
+        edition = "2024",
+        proc_macro_deps = all_crate_deps(proc_macro_dev = True),
+        deps = all_crate_deps(normal_dev = True) + [":pi-walker"],
+    )
+    for name in [
+        "parallel",
+        "perf",
+    ]
+]