refactor: simplify Alpine CI with node image, corepack, and smart linker scripts

- Use node:22-alpine3.21 image instead of alpine:3.21 to get Node.js
  with TypeScript support pre-installed
- Use corepack to install pnpm, respecting packageManager in package.json
- Update .cargo linker scripts to detect Linux hosts and use system cc
  directly, removing the need for the sed workaround in CI
- Split Rust setup into rustup install + toolchain install from
  rust-toolchain.toml

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: branchseer

.cargo/config.toml

@@ -4,8 +4,8 @@ rustflags = ["--cfg", "tokio_unstable", "-D", "warnings"]
 [unstable]
 bindeps = true
 
-# Linker wrappers for cross-compiling bindep targets (fspy_test_bin) via cargo-zigbuild.
-# On native Linux the system linker can handle musl targets; these are needed on non-Linux hosts.
+# Linker wrappers for musl targets. On Linux hosts these use the system cc directly;
+# on non-Linux hosts (macOS, Windows) they cross-compile via cargo-zigbuild.
 [target.x86_64-unknown-linux-musl]
 rustflags = ["-C", "linker=.cargo/zigcc-x86_64-unknown-linux-musl"]
 

.cargo/zigcc-aarch64-unknown-linux-musl

@@ -1,2 +1,7 @@
 #!/bin/sh
+# Linker wrapper for aarch64-unknown-linux-musl targets.
+# On Linux, use the system cc directly. On other hosts, cross-compile via cargo-zigbuild.
+if [ "$(uname -s)" = "Linux" ]; then
+  exec cc "$@"
+fi
 exec cargo-zigbuild zig cc -- -fno-sanitize=all -target aarch64-linux-musl "$@"

.cargo/zigcc-x86_64-unknown-linux-musl

@@ -1,2 +1,7 @@
 #!/bin/sh
+# Linker wrapper for x86_64-unknown-linux-musl targets.
+# On Linux, use the system cc directly. On other hosts, cross-compile via cargo-zigbuild.
+if [ "$(uname -s)" = "Linux" ]; then
+  exec cc "$@"
+fi
 exec cargo-zigbuild zig cc -- -fno-sanitize=all -target x86_64-linux-musl "$@"

.github/workflows/ci.yml

@@ -139,7 +139,7 @@ jobs:
     name: Test (musl)
     runs-on: ubuntu-latest
     container:
-      image: alpine:3.21
+      image: node:22-alpine3.21
       options: --shm-size=256m # shm_io tests need bigger shared memory
     steps:
       - name: Install Alpine dependencies
@@ -151,28 +151,19 @@ jobs:
           persist-credentials: false
           submodules: true
 
-      # Alpine's Node.js package is compiled without TypeScript type-stripping.
-      # Install the official Node.js musl binary which includes full TypeScript support.
-      - name: Install Node.js from official distribution
+      - name: Install rustup
         run: |
-          NODE_VERSION=v$(cat .node-version)
-          curl -fsSL "https://unofficial-builds.nodejs.org/download/release/${NODE_VERSION}/node-${NODE_VERSION}-linux-x64-musl.tar.gz" | tar -xz -C /usr/local --strip-components=1
-
-      - name: Install Rust
-        run: |
-          curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh -s -- -y --default-toolchain nightly-2026-03-05
+          curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh -s -- -y --default-toolchain none
           echo "$HOME/.cargo/bin" >> "$GITHUB_PATH"
 
+      - name: Install Rust toolchain
+        run: rustup show
+
       - name: Install pnpm and Node tools
         run: |
-          npm install -g pnpm
+          corepack enable
           pnpm install
 
-      # Remove the zig cross-compilation config from .cargo/config.toml — in Alpine,
-      # the system cc is already musl-based, so no cross-compilation linker is needed.
-      - name: Remove zig linker config for native musl
-        run: sed -i '/\[target.*musl\]/,/^$/d' .cargo/config.toml
-
       - run: cargo test --no-fail-fast
 
   fmt: