feat(phase21.5): Stage-B parser loop fix + delegate path stabilization

## 修正内容

### 1. Stage-B パーサー修正（偶然の回避）
- **ファイル**:
  - `lang/src/compiler/parser/expr/parser_expr_box.hako`
  - `lang/src/compiler/parser/stmt/parser_control_box.hako`
- **問題**: ネストループで gpos が正しく進まず、loop の cond/body が壊れる
- **回避策**: new 式のメソッドチェーン処理追加で別ループを導入
- **結果**: MIR 生成が変わって VM gpos バグを回避

### 2. delegate パス動作確認
- **テスト**: `/tmp/loop_min.hako` → rc=10 ✅
- **MIR構造**: 正しい PHI/compare/binop を生成
- **チェーン**: hakorune parser → Rust delegate → LLVM EXE 完動

### 3. ドキュメント追加
- `docs/development/analysis/` - delegate 分析
- `docs/development/guides/` - ループテストガイド
- `docs/development/testing/` - Stage-B 検証報告

### 4. カナリーテスト追加
- `tools/smokes/v2/profiles/quick/core/phase2100/` 配下に複数追加
- emit_boxcall_length_canary_vm.sh
- stageb_parser_loop_json_canary_vm.sh
- 他

### 受け入れ基準
- ✅ delegate パス: rc=10 返す
- ✅ FORCE パス: rc=10 返す（既存）
- ✅ MIR 構造: 正しい PHI incoming と compare
- ✅ 既定挙動: 不変（dev トグルのみ）

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

README.md

@@ -32,14 +32,17 @@ Architecture notes
 
 Execution Status (Feature Additions Pause)
 - Active
-  - `--backend llvm` (Python/llvmlite harness; AOT object emit)
-  - `--backend vm` (PyVM harness)
+  - `--backend llvm` (ny-llvmc crate backend; llvmlite harness is internal) — AOT object/EXE line
+  - `--backend vm` (VM / reference semantics)
 - Inactive/Sealed
   - `--backend cranelift`, `--jit-direct` (sealed; use LLVM harness)
   - AST interpreter (legacy) is gated by feature `interpreter-legacy` and excluded from default builds (Rust VM + LLVM are the two main lines)
 
 Quick pointers
-- Emit object with harness: set `NYASH_LLVM_USE_HARNESS=1` and `NYASH_LLVM_OBJ_OUT=<path>` (defaults in tools use `tmp/`).
+- Emit object/EXE with crate backend:
+  - `tools/ny_mir_builder.sh --in /path/mir.json --emit obj -o a.o`
+  - `tools/ny_mir_builder.sh --in /path/mir.json --emit exe -o a.out`
+  - auto-selects `ny-llvmc` when present（`NYASH_LLVM_BACKEND=crate` 明示でも可）
 - Run PyVM: `NYASH_VM_USE_PY=1 $NYASH_BIN --backend vm apps/APP/main.hako`.
 
 Program(JSON v0) → MIR(JSON)
@@ -65,6 +68,7 @@ Phase‑15 (2025‑09) update
 - 推奨トグル: `NYASH_LLVM_USE_HARNESS=1`, `NYASH_PARSER_TOKEN_CURSOR=1`, `NYASH_JSON_PROVIDER=ny`, `NYASH_SELFHOST_EXEC=1`。
 
 Developer quickstart: see `docs/guides/getting-started.md`. Changelog highlights: `CHANGELOG.md`.
+ny‑llvm line quickstart: `docs/development/testing/selfhost_exe_stageb_quick_guide.md`（Stage‑B → MirBuilder → ny‑llvmc → EXE）
 User Macros (Phase 2): `docs/guides/user-macros.md`
 Exceptions (postfix catch/cleanup): `docs/guides/exception-handling.md`
 ScopeBox & MIR hints: `docs/guides/scopebox.md`
@@ -261,12 +265,12 @@ cargo build --release --features cranelift-jit
 - Maximum performance
 - Easy distribution
 
-### 4. **Native Binary (LLVM AOT, llvmlite harness)**
+### 4. **Native Binary (LLVM AOT, ny-llvmc crate backend)**
 ```bash
 # Build harness + CLI (no LLVM_SYS_180_PREFIX needed)
 cargo build --release -p nyash-llvm-compiler && cargo build --release --features llvm
 
-# Emit and run native executable via harness
+# Emit and run native executable via crate backend (ny-llvmc)
 NYASH_LLVM_USE_HARNESS=1 \
 NYASH_NY_LLVM_COMPILER=target/release/ny-llvmc \
 NYASH_EMIT_EXE_NYRT=target/release \
@@ -298,7 +302,7 @@ tools/smoke_aot_vs_vm.sh examples/aot_min_string_len.hako
 The WASM/browser path is currently not maintained and is not part of CI. The older playground and guides are kept for historical reference only.
 
 - Source (archived): `projects/nyash-wasm/` (build not guaranteed)
-- Current focus: VM (Rust) and LLVM (llvmlite harness)
+- Current focus: VM (Rust) and LLVM (ny-llvmc crate backend; llvmlite harness is internal)
 - If you experiment locally, see the project README and `projects/nyash-wasm/build.sh` (wasm-pack required). No support guarantees.
 
 ---
@@ -323,7 +327,8 @@ Key options (minimal)
 - `--target <triple>` (only when needed)
 
 Notes
-- LLVM AOT uses Python llvmlite harness. Ensure Python3 + llvmlite and `ny-llvmc` are available (built via `cargo build -p nyash-llvm-compiler`). No `LLVM_SYS_180_PREFIX` required.
+- LLVM AOT main line is the ny-llvmc crate backend. ny-llvmc internally delegates object emission to the Python llvmlite harness; end users should invoke ny-llvmc (or tools/ny_mir_builder.sh) rather than calling the harness directly.
+- Ensure `ny-llvmc` is built (`cargo build -p nyash-llvm-compiler`) and Python3 is available for the internal harness. No `LLVM_SYS_180_PREFIX` required.
 - Apps that open a GUI may show a window during AOT emission; close it to continue.
 - On WSL if the window doesn’t show, see `docs/guides/cranelift_aot_egui_hello.md` (Wayland→X11).