bazel: Register Pigweed toolchains we use

Bug: 362827235
Change-Id: I862326609d761cacc2a14c54f55174384ddc656e
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/examples/+/238477
Commit-Queue: Auto-Submit <auto-submit@pigweed-service-accounts.iam.gserviceaccount.com>
Pigweed-Auto-Submit: Ted Pudlik <tpudlik@google.com>
Presubmit-Verified: CQ Bot Account <pigweed-scoped@luci-project-accounts.iam.gserviceaccount.com>
Lint: Lint 🤖 <android-build-ayeaye@system.gserviceaccount.com>
Reviewed-by: Taylor Cramer <cramertj@google.com>
diff --git a/MODULE.bazel b/MODULE.bazel
index 6d16a74..85a3b70 100644
--- a/MODULE.bazel
+++ b/MODULE.bazel
@@ -69,3 +69,14 @@
     strip_prefix = "cmsis-core-5.4.0_cm4",
     urls = ["https://github.com/STMicroelectronics/cmsis_core/archive/refs/tags/v5.4.0_cm4.tar.gz"],
 )
+
+register_toolchains(
+    # Toolchain for the Pico 2
+    "@pigweed//pw_toolchain:cc_toolchain_cortex-m0",
+    # Toolchain for the STM32 Discovery Board
+    "@pigweed//pw_toolchain/arm_gcc:arm_gcc_cc_toolchain_cortex-m4",
+    # Host toolchains
+    "@pigweed//pw_toolchain/host_clang:host_cc_toolchain_linux",
+    "@pigweed//pw_toolchain/host_clang:host_cc_toolchain_macos",
+    dev_dependency = True,
+)