ci: add GitHub Actions workflow; runner: prefer PyVM in selfhost paths; stage3: add LLVM + bridge acceptance smokes; docs: update env flags

.github/workflows/ci.yml

@@ -0,0 +1,51 @@
+name: nyash-ci
+
+on:
+  push:
+  pull_request:
+
+jobs:
+  build-and-smoke:
+    runs-on: ubuntu-latest
+    timeout-minutes: 30
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Install LLVM 18 (apt.llvm.org)
+        run: |
+          sudo apt-get update
+          sudo apt-get install -y wget gnupg lsb-release
+          wget https://apt.llvm.org/llvm.sh
+          chmod +x llvm.sh
+          sudo ./llvm.sh 18
+
+      - name: Set LLVM env
+        run: echo "LLVM_SYS_180_PREFIX=$(llvm-config-18 --prefix)" >> "$GITHUB_ENV"
+
+      - name: Ensure Python3
+        run: sudo apt-get install -y python3
+
+      - name: Set up Rust
+        uses: dtolnay/rust-toolchain@stable
+
+      - name: Cache Rust build
+        uses: Swatinem/rust-cache@v2
+        with:
+          cache-targets: true
+
+      - name: Build (LLVM feature)
+        run: cargo build --release --features llvm
+
+      - name: Curated LLVM smokes
+        run: ./tools/smokes/curated_llvm.sh
+
+      - name: Curated LLVM Stage-3 smokes
+        run: ./tools/smokes/curated_llvm_stage3.sh
+
+      - name: Bridge Stage-3 acceptance (JSON v0 pipe)
+        run: ./tools/ny_stage3_bridge_accept_smoke.sh
+
+      - name: Curated LLVM Stage-3 smokes (PHI-off)
+        run: ./tools/smokes/curated_llvm_stage3.sh --phi-off
+