ci: cover aarch64-windows via Linux cross-compile, drop flaky preview runner

The windows-11-arm preview runner exits 'zig build' with no output (toolchain
instability, not a code bug — aarch64-windows cross-compiles clean from Linux:
verified zig build + zig cc -lpsapi both produce valid ARM64 PE binaries). It was
continue-on-error but still showed a red check on every commit. Replace the native
aarch64 matrix entry with a reliable cross-windows-aarch64 job (build-only; runtime
tests stay on native windows x86_64 + the Linux/macOS nix checks).

Author: pmarreck

.github/workflows/ci.yml

@@ -80,12 +80,14 @@ jobs:
         include:
           - runner: windows-latest
             arch: x86_64
-          - runner: windows-11-arm
-            arch: aarch64
 
     runs-on: ${{ matrix.runner }}
     name: windows (${{ matrix.arch }})
-    continue-on-error: true  # ARM runner may be in preview
+    # aarch64-windows is covered by the cross-windows-aarch64 job below (reliable
+    # Linux cross-compile) instead of the GitHub windows-11-arm preview runner,
+    # which exits zig build with no output (toolchain instability, not a code bug —
+    # the same target cross-compiles clean from Linux). Revisit native ARM when
+    # the runner leaves preview.
 
     steps:
       - uses: actions/checkout@v6
@@ -183,3 +185,39 @@ jobs:
         with:
           name: printable-binary-c-${{ matrix.arch }}-windows
           path: printable-binary-c.exe
+
+  # aarch64-windows build coverage via reliable Linux cross-compilation, in
+  # place of the flaky windows-11-arm preview runner. Build-only (a cross-built
+  # Windows binary can't execute on the Linux runner); runtime tests are covered
+  # natively on windows x86_64 above and on Linux/macOS via the nix checks.
+  cross-windows-aarch64:
+    runs-on: ubuntu-latest
+    name: cross (aarch64-windows)
+    steps:
+      - uses: actions/checkout@v6
+
+      - name: Install Zig (x86_64-linux host)
+        shell: bash
+        run: |
+          set -euo pipefail
+          version="0.16.0"
+          curl -fsSL "https://ziglang.org/download/${version}/zig-x86_64-linux-${version}.tar.xz" -o "$RUNNER_TEMP/zig.tar.xz"
+          mkdir -p "$RUNNER_TEMP/zig"
+          tar -xf "$RUNNER_TEMP/zig.tar.xz" -C "$RUNNER_TEMP/zig"
+          zig_dir="$(find "$RUNNER_TEMP/zig" -mindepth 1 -maxdepth 1 -type d | head -n 1)"
+          echo "$zig_dir" >> "$GITHUB_PATH"
+          "$zig_dir/zig" version
+
+      - name: Cross-compile aarch64-windows (Zig CLI + lib)
+        run: zig build -Dtarget=aarch64-windows -Doptimize=ReleaseFast
+
+      - name: Cross-compile aarch64-windows C CLI (zig cc, -lpsapi)
+        run: zig cc -target aarch64-windows-gnu -O3 -I. -o printable-binary-c-aarch64-windows.exe src/printable_binary.c -lpsapi
+
+      - name: Upload aarch64-windows binaries
+        uses: actions/upload-artifact@v6
+        with:
+          name: printable-binary-aarch64-windows
+          path: |
+            zig-out/bin/printable-binary-zig.exe
+            printable-binary-c-aarch64-windows.exe

.gitignore

@@ -39,3 +39,6 @@ ZIG_0.15_TO_0.16_MIGRATION.md
 !bin/utf16to8
 AGENTS*.md
 CLAUDE*.md
+# Local convenience symlink to ~/dotfiles (external target — must not be committed
+# into a published repo; broke the GitHub Pages build as a dangling symlink).
+jj_cheatsheet.md