feat(llvm): Phase 131-13/14 - MIR JSON順序修正 & 2パスsnapshot解決

## Phase 131-13: MIR JSON 命令順序修正
- copy 遅延ロジック削除（~80行）
- MIR の def→use 順序をそのまま出力（SSOT）
- PHI 先頭集約のみ維持

## Phase 131-14: jump-only block 2パス snapshot 解決
- Pass A: jump-only block はメタ記録のみ
- Pass B: resolve_jump_only_snapshots() で CFG ベース解決
- path compression で連鎖を効率的に解決
- サイクル検出で Fail-Fast

## 結果
- ✅ STRICT モードでエラーなし
- ✅ bb7 が bb5 の snapshot を正しく継承
- ✅ ループが正しく動作（1, 2 出力確認）
- ⚠️ print/concat で segfault（別問題、次Phase）

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

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

src/llvm_py/resolver.py

@@ -3,7 +3,7 @@ Resolver API (Python version)
 Based on src/backend/llvm/compiler/codegen/instructions/resolver.rs
 """
 
-from typing import Dict, Optional, Any, Tuple
+from typing import Dict, Optional, Any, Tuple, Set
 import os
 from trace import phi as trace_phi
 from trace import values as trace_values
@@ -63,6 +63,8 @@ class Resolver:
         self.block_phi_incomings = {}
         # P0-1: SSOT for end-of-block values (snapshots)
         self.block_end_values = {}
+        # P0-3: Circular reference detection (hang prevention)
+        self._visited: Set[Tuple[int, int]] = set()
 
     def mark_string(self, value_id: int) -> None:
         try:
@@ -75,7 +77,81 @@ class Resolver:
             return int(value_id) in self.string_ids
         except Exception:
             return False
-    
+
+    def _check_cycle(self, block_id: int, value_id: int):
+        """P0-3: Circular reference detection (hang prevention)"""
+        key = (block_id, value_id)
+        if key in self._visited:
+            raise RuntimeError(
+                f"[LLVM_PY] Circular reference detected: bb{block_id} v{value_id}"
+            )
+        self._visited.add(key)
+
+    def resolve_cur(self, block_id: int, value_id: int, vmap_cur: Dict[int, ir.Value]) -> ir.Value:
+        """P0-1: Same-block instruction lowering (vmap_cur as primary source)
+
+        Used for lowering instructions within the same basic block where the value
+        is defined and used. Checks vmap_cur first, then applies fail-fast checks.
+
+        Args:
+            block_id: Current basic block ID
+            value_id: Value ID to resolve
+            vmap_cur: Current block's value map (def->use tracking)
+
+        Returns:
+            LLVM IR value (i64)
+        """
+        # 1. Check vmap_cur first
+        val = vmap_cur.get(value_id)
+        if val is not None:
+            return val
+
+        # 2. Fail-Fast: def_blocks has bb but vmap_cur doesn't → lowerer bug
+        if value_id in self.def_blocks and block_id in self.def_blocks[value_id]:
+            if os.environ.get('NYASH_LLVM_STRICT') == '1':
+                raise RuntimeError(
+                    f"[LLVM_PY/STRICT] resolve_cur: v{value_id} defined in bb{block_id} "
+                    f"but not in vmap_cur. Lowerer order bug?"
+                )
+
+        # 3. vmap_cur miss → undefined error
+        if os.environ.get('NYASH_LLVM_STRICT') == '1':
+            raise RuntimeError(
+                f"[LLVM_PY/STRICT] resolve_cur: v{value_id} not found in bb{block_id} vmap_cur. "
+                f"Available: {sorted(vmap_cur.keys())}"
+            )
+
+        # Non-STRICT: fallback to 0
+        return ir.Constant(ir.IntType(64), 0)
+
+    def resolve_incoming(self, pred_block_id: int, value_id: int) -> ir.Value:
+        """P0-2: PHI incoming resolution (snapshot-only reference)
+
+        Used for resolving PHI incoming values from predecessor blocks.
+        Only looks at block_end_values snapshot, never vmap_cur.
+
+        Args:
+            pred_block_id: Predecessor block ID
+            value_id: Value ID to resolve from predecessor
+
+        Returns:
+            LLVM IR value (i64)
+        """
+        snapshot = self.block_end_values.get(pred_block_id, {})
+        val = snapshot.get(value_id)
+        if val is not None:
+            return val
+
+        # Fail-Fast: snapshot miss → structural bug
+        if os.environ.get('NYASH_LLVM_STRICT') == '1':
+            raise RuntimeError(
+                f"[LLVM_PY/STRICT] resolve_incoming: v{value_id} not in bb{pred_block_id} snapshot. "
+                f"Available: {sorted(snapshot.keys())}"
+            )
+
+        # Non-STRICT: fallback to 0
+        return ir.Constant(ir.IntType(64), 0)
+
     def resolve_i64(
         self,
         value_id: int,