ci: add macOS arm64 wheel build workflow

Builds mlx wheels for Python 3.11 and 3.12 on macos-14 (arm64)
on push to main, metal-*, q-*, attn-mask-fix, fix-rope branches
or via workflow_dispatch. Wheels uploaded as artifacts (30d retention).
Tagged commits (v*) also publish a GitHub Release.

.github/workflows/build-wheels.yml

@@ -0,0 +1,81 @@
+name: Build macOS arm64 wheels
+
+on:
+  push:
+    branches:
+      - main
+      - 'metal-*'
+      - 'q-*'
+      - attn-mask-fix
+      - fix-rope
+  workflow_dispatch:
+    inputs:
+      branch_to_build:
+        description: 'Branch to build (optional, defaults to current ref)'
+        required: false
+        default: ''
+
+concurrency:
+  group: build-${{ github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  build:
+    name: Build wheel (Python ${{ matrix.python }})
+    runs-on: macos-14
+    timeout-minutes: 60
+    strategy:
+      fail-fast: false
+      matrix:
+        python: ['3.11', '3.12']
+    env:
+      CMAKE_BUILD_PARALLEL_LEVEL: '4'
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+        with:
+          ref: ${{ github.event.inputs.branch_to_build || github.ref }}
+          submodules: recursive
+
+      - name: Set up Python ${{ matrix.python }}
+        uses: actions/setup-python@v5
+        with:
+          python-version: ${{ matrix.python }}
+
+      - name: Cache pip
+        uses: actions/cache@v4
+        with:
+          path: |
+            ~/.cache/pip
+            ~/Library/Caches/pip
+          key: pip-${{ runner.os }}-py${{ matrix.python }}-${{ hashFiles('CMakeLists.txt', 'setup.py', 'pyproject.toml') }}
+          restore-keys: |
+            pip-${{ runner.os }}-py${{ matrix.python }}-
+
+      - name: Install build dependencies
+        run: |
+          python -m pip install -U pip wheel build setuptools cmake nanobind
+
+      - name: Build wheel
+        run: |
+          mkdir -p ./wheels
+          pip wheel --no-deps . -w ./wheels
+
+      - name: List built wheels
+        run: ls -lh ./wheels
+
+      - name: Upload wheel artifact
+        uses: actions/upload-artifact@v4
+        with:
+          name: mlx-${{ github.ref_name }}-py${{ matrix.python }}-wheels
+          path: ./wheels/*.whl
+          retention-days: 30
+          if-no-files-found: error
+
+      - name: Create GitHub Release (on tag)
+        if: startsWith(github.ref, 'refs/tags/v')
+        uses: softprops/action-gh-release@v2
+        with:
+          files: ./wheels/*.whl
+          fail_on_unmatched_files: false
+          generate_release_notes: true