ci: add GitHub Actions workflow on self-hosted Apple Silicon runners

Add lint (ruff) and pytest jobs on the self-hosted Apple Silicon runners
[self-hosted, macos, tahoe, ARM64]; the DSL/composite tests require Metal
and MLX. Pin actions/checkout to a commit SHA and install uv via its
official install script. Guard jobs to apple/coreai-torch so forks don't
run on the self-hosted runners.

Author: DawerG

.github/workflows/ci.yml

@@ -0,0 +1,37 @@
+name: CI
+
+on:
+  pull_request:
+    branches: [main]
+  push:
+    branches: [main]
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  lint:
+    if: github.repository == 'apple/coreai-torch'
+    runs-on: [self-hosted, macos, tahoe, ARM64]
+    timeout-minutes: 15
+    steps:
+      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6
+      - name: Ensure uv
+        run: |
+          command -v uv >/dev/null 2>&1 || curl -LsSf https://astral.sh/uv/install.sh | sh
+          echo "$HOME/.local/bin" >> "$GITHUB_PATH"
+      - run: uv run --extra dev ruff check .
+      - run: uv run --extra dev ruff format --check .
+
+  python-test:
+    if: github.repository == 'apple/coreai-torch'
+    runs-on: [self-hosted, macos, tahoe, ARM64]
+    timeout-minutes: 60
+    steps:
+      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6
+      - name: Ensure uv
+        run: |
+          command -v uv >/dev/null 2>&1 || curl -LsSf https://astral.sh/uv/install.sh | sh
+          echo "$HOME/.local/bin" >> "$GITHUB_PATH"
+      - run: uv run --extra test pytest tests/ -n auto -m "not slow"