docs: Phase 263 P0 完了記録（Pattern2 fallback 修正）

- 10-Now.md: Phase 263 P0 完了記録を追加（最上部に配置）
- phase-263/README.md: 詳細な実装記録・検証結果を作成
- 30-Backlog.md: Phase 263+ planned 項目を追加
  - Pattern2 LoopBodyLocal promotion（seg）
  - PromoteDecision API hardening（構造で迷子防止）
- phase263_p0_pattern2_seg_vm.sh: smoke test スクリプト改善

検証結果:
- cargo test --lib: 1368/1368 PASS ✅
- quick smoke: 45/46 PASS ✅ (大幅改善)
- Pattern2 が正しく abort することを確認

tools/smokes/v2/profiles/integration/apps/phase263_p0_pattern2_seg_vm.sh

@@ -1,9 +1,23 @@
-#!/usr/bin/env bash
-set -euo pipefail
+#!/bin/bash
+# Phase 263 P0 - Pattern2 LoopBodyLocal seg fallback (VM backend)
+# Tests: Pattern2 rejects "seg" (reassigned body-local) → Pattern1 fallback
 
-SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
-source "$SCRIPT_DIR/../../common.sh"
+HAKO_FILE="apps/tests/phase263_p0_pattern2_seg_min.hako"
+BACKEND="vm"
+EXPECTED_OUTPUT="0"
 
-APP_PATH="apps/tests/phase263_p0_pattern2_seg_min.hako"
+ACTUAL_OUTPUT=$(HAKO_JOINIR_STRICT=1 ./target/release/hakorune --backend "$BACKEND" "$HAKO_FILE" 2>&1 | tail -1 | grep -E '^[0-9]+$')
 
-run_vm_test "$APP_PATH" "phase263_p0_pattern2_seg_min"
+if [ "$ACTUAL_OUTPUT" = "$EXPECTED_OUTPUT" ]; then
+    echo "✅ PASS: phase263_p0_pattern2_seg_vm"
+    exit 0
+else
+    echo "❌ FAIL: phase263_p0_pattern2_seg_vm"
+    echo "Expected:"
+    echo "$EXPECTED_OUTPUT"
+    echo "Got:"
+    echo "$ACTUAL_OUTPUT"
+    echo "---Full output (last 80 lines):---"
+    HAKO_JOINIR_STRICT=1 ./target/release/hakorune --backend "$BACKEND" "$HAKO_FILE" 2>&1 | tail -n 80
+    exit 1
+fi