feat(llvm): Phase 131-11-H/12 - ループキャリアPHI型修正 & vmap snapshot SSOT

## Phase 131-11-H: ループキャリアPHI型修正
- PHI生成時に初期値（entry block）の型のみ使用
- backedge の値を型推論に使わない（循環依存回避）
- NYASH_CARRIER_PHI_DEBUG=1 でトレース

## Phase 131-12-P0: def_blocks 登録 & STRICT エラー化
- safe_vmap_write() で PHI 上書き保護
- resolver miss を STRICT でエラー化（フォールバック 0 禁止）
- def_blocks 自動登録

## Phase 131-12-P1: vmap_cur スナップショット実装
- DeferredTerminator 構造体（block, term_ops, vmap_snapshot）
- Pass A で vmap_cur をスナップショット
- Pass C でスナップショット復元（try-finally）
- STRICT モード assert

## 結果
- ✅ MIR PHI型: Integer（正しい）
- ✅ VM: Result: 3
- ✅ vmap snapshot 機構: 動作確認
- ⚠️ LLVM: Result: 0（別のバグ、次Phase で調査）

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

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

docs/development/current/main/phase131-3-llvm-lowering-inventory.md

@@ -10,7 +10,7 @@
 | A | `apps/tests/phase87_llvm_exe_min.hako` | ✅ | ✅ | ✅ | **PASS** - Simple return 42, no BoxCall, exit code verified |
 | B | `apps/tests/loop_min_while.hako` | ✅ | ✅ | ✅ | **PASS** - Loop/PHI path runs end-to-end (Phase 131-10): prints `0,1,2` and exits |
 | B2 | `/tmp/case_b_simple.hako` | ✅ | ✅ | ✅ | **PASS** - Simple print(42) without loop works |
-| C | `apps/tests/llvm_stage3_loop_only.hako` | ❌ | - | - | **TAG-EMIT** - Complex loop (break/continue) fails JoinIR pattern matching |
+| C | `apps/tests/llvm_stage3_loop_only.hako` | ✅ | ✅ | ⚠️ | **TAG-RUN** - Runs but result mismatch (VM ok / LLVM wrong) |
 
 ## Root Causes Identified
 
@@ -175,7 +175,7 @@ RC: 0
 
 ---
 
-### 4. TAG-EMIT: JoinIR Pattern Coverage Gap (Case C) - ✅ ROOT CAUSE IDENTIFIED
+### 4. Case C: loop(true) + break/continue - from TAG-EMIT to TAG-RUN
 
 **File**: `apps/tests/llvm_stage3_loop_only.hako`
 
@@ -195,29 +195,22 @@ static box Main {
 }
 ```
 
-**MIR Compilation**: FAILURE
-```
-❌ MIR compilation error: [joinir/freeze] Loop lowering failed:
-   JoinIR does not support this pattern, and LoopBuilder has been removed.
-Function: main
-Hint: This loop pattern is not supported. All loops must use JoinIR lowering.
-```
+**MIR Compilation**: SUCCESS（Phase 131-11）
 
-**Root Cause** (Phase 131-11 Analysis):
-1. **Pattern Gap**: `loop(true)` (infinite loop) not recognized by Patterns 1-4
-2. **Loop Variable Extraction Fails**: `extract_loop_variable_from_condition()` expects binary comparison (`i < 3`), not boolean literal (`true`)
-3. **Classification Priority Bug**: `has_continue = true` routes to Pattern 4, but Pattern 4 expects a loop variable
+**What changed**:
+- Pattern gap was resolved by introducing a dedicated infinite-loop early-exit pattern (Phase 131-11 A–C).
+- A loop-carrier PHI type-cycle bug was fixed by seeding the PHI type from the entry(init) value (Phase 131-11 H).
+  - Root cause report: `docs/development/current/main/phase-131-11-g-phi-type-bug-report.md`
 
-**Failure Flow**:
-```
-1. LoopPatternContext::new() detects has_continue=true, has_break=true
-2. classify() returns Pattern4Continue (because has_continue)
-3. Pattern4::can_lower() tries extract_loop_variable_from_condition(BoolLiteral(true))
-4. ❌ Fails: "Unsupported loop condition pattern"
-5. No pattern matches → freeze() error
-```
+**Current issue**: **TAG-RUN (wrong result)**  
+VM and MIR look correct, but LLVM output does not match expected result for Case C.
 
-**Solution** (Phase 131-11 Recommended):
+**Next actions**:
+- Dump LLVM IR (`NYASH_LLVM_DUMP_IR=...`) and trace PHI/value resolution (`NYASH_LLVM_TRACE_PHI=1`, `NYASH_LLVM_TRACE_VALUES=1`).
+- Reduce Case C to isolate whether the bug is “loop value” or “string concat/print path”:
+  - `return counter` (no string concat)
+  - `print(counter)` (no `"Result: " + ...`)
+  - Compare with VM and inspect the IR use-sites.
 - Add `is_infinite_loop: bool` feature to `LoopFeatures` (detect `loop(true)`).
 - Fix classification so `has_break && has_continue` does not route to Pattern 4.
 - Introduce a dedicated pattern kind + lowerer for **infinite loop + early-exit (+ optional continue)**: