Merge selfhosting-dev into main (Core-13 pure CI/tests + LLVM bridge) (#126)

* WIP: sync before merging origin/main

* fix: unify using/module + build CLI; add missing helper in runner; build passes; core smokes green; jit any.len string now returns 3

* Apply local changes after merging main; keep docs/phase-15 removed per main; add phase-15.1 docs and tests

* Remove legacy docs/phase-15/README.md to align with main

* integration: add Core-13 pure CI, tests, and minimal LLVM execute bridge (no docs) (#125)

Co-authored-by: Tomoaki <tomoaki@example.com>

---------

Co-authored-by: Selfhosting Dev <selfhost@example.invalid>
Co-authored-by: Tomoaki <tomoaki@example.com>

.github/pull_request_template.md

@@ -9,3 +9,8 @@
 - [ ] 回帰CI green（env直読み検出なし）
 - [ ] stats: fallback率・理由が記録される
 
+### Selfhosting‑dev Gate（このブランチ向け）
+- [ ] `bash tools/selfhost_vm_smoke.sh` が PASS（plugins 無効）
+- [ ] `docs/CONTRIBUTING-MERGE.md` の境界方針を満たす（Cranelift実装差分は専用ブランチ）
+- 影響範囲: runner / interpreter / vm / tools / docs
+- Feature gates（該当時）: `cranelift-jit`, その他（記述）

.github/workflows/core13-pure-llvm.yml

@@ -0,0 +1,36 @@
+name: Core-13 Pure CI (LLVM)
+
+on:
+  push:
+  pull_request:
+
+jobs:
+  test-core13-pure-llvm:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Install Rust (stable)
+        uses: dtolnay/rust-toolchain@stable
+
+      - name: Cache cargo
+        uses: Swatinem/rust-cache@v2
+
+      - name: Install LLVM 18 (llvm-config-18)
+        run: |
+          sudo apt-get update
+          sudo apt-get install -y curl ca-certificates lsb-release wget gnupg
+          curl -fsSL https://apt.llvm.org/llvm.sh -o llvm.sh
+          chmod +x llvm.sh
+          sudo ./llvm.sh 18
+          llvm-config-18 --version
+
+      - name: Run tests with Core-13 pure mode + LLVM
+        env:
+          NYASH_MIR_CORE13_PURE: "1"
+        run: |
+          export LLVM_SYS_180_PREFIX="$(llvm-config-18 --prefix)"
+          export LLVM_SYS_181_PREFIX="$(llvm-config-18 --prefix)"
+          cargo test --features llvm --all-targets --no-fail-fast
+

.github/workflows/core13-pure.yml

@@ -0,0 +1,27 @@
+name: Core-13 Pure CI
+
+on:
+  push:
+  pull_request:
+
+jobs:
+  test-core13-pure:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Install Rust (stable)
+        uses: dtolnay/rust-toolchain@stable
+
+      - name: Cache cargo
+        uses: Swatinem/rust-cache@v2
+
+      - name: Build (release)
+        run: cargo build --release
+
+      - name: Run tests with Core-13 pure mode
+        env:
+          NYASH_MIR_CORE13_PURE: "1"
+        run: cargo test --all-targets --no-fail-fast
+

.github/workflows/selfhost-minimal.yml

@@ -0,0 +1,54 @@
+name: Selfhost Minimal Smoke
+
+on:
+  push:
+    branches: [ selfhosting-dev ]
+    paths:
+      - 'apps/selfhost-minimal/**'
+      - 'src/**'
+      - 'tools/**'
+      - 'Cargo.toml'
+      - 'Cargo.lock'
+      - '.github/workflows/selfhost-minimal.yml'
+      - 'docs/**'
+  pull_request:
+    branches: [ selfhosting-dev ]
+    paths:
+      - 'apps/selfhost-minimal/**'
+      - 'src/**'
+      - 'tools/**'
+      - 'Cargo.toml'
+      - 'Cargo.lock'
+      - 'docs/**'
+
+jobs:
+  selfhost-minimal:
+    runs-on: ubuntu-latest
+    timeout-minutes: 10
+    env:
+      CARGO_TERM_COLOR: always
+      NYASH_DISABLE_PLUGINS: '1'
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Setup Rust (stable)
+        uses: dtolnay/rust-toolchain@stable
+
+      - name: Cache cargo registry and build
+        uses: actions/cache@v4
+        with:
+          path: |
+            ~/.cargo/registry
+            ~/.cargo/git
+            target
+          key: ${{ runner.os }}-cargo-${{ hashFiles('**/Cargo.lock') }}
+          restore-keys: |
+            ${{ runner.os }}-cargo-
+
+      - name: Build (release, cranelift-jit)
+        run: cargo build --release --features cranelift-jit
+
+      - name: Run selfhost-minimal smoke
+        run: bash tools/selfhost_vm_smoke.sh
+