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/builders/function_lower.py

@@ -279,6 +279,10 @@ def lower_function(builder, func_data: Dict[str, Any]):
     from builders.block_lower import lower_blocks as _lower_blocks
     _lower_blocks(builder, func, block_by_id, order, loop_plan)
 
+    # Phase 131-14-B Pass B: Resolve jump-only block snapshots (BEFORE PHI finalization)
+    from builders.block_lower import resolve_jump_only_snapshots as _resolve_jump_only_snapshots
+    _resolve_jump_only_snapshots(builder, block_by_id)
+
     # Optional: capture lowering ctx for downstream helpers
     try:
         builder.ctx = dict(
@@ -300,7 +304,7 @@ def lower_function(builder, func_data: Dict[str, Any]):
     except Exception:
         pass
 
-    # Phase 131-4 Pass B: Finalize PHIs (wires incoming edges)
+    # Phase 131-4 Pass B (now Pass B2): Finalize PHIs (wires incoming edges)
     _finalize_phis(builder)
 
     # Phase 131-4 Pass C: Lower deferred terminators (after PHIs are placed)