Phase 10.7 - JIT統計とイベント機能の完成

主要な実装:
- PHI(b1)統計追跡: phi_total_slots/phi_b1_slotsをJSON出力
- 関数単位統計API: JitStatsBox.perFunction()で詳細統計取得
- JITイベントシステム: compile/execute/fallback/trapをJSONL形式で記録
- Store/Load命令対応: ローカル変数を含む関数のJIT実行が可能に

新しいBox:
- JitStatsBox: JIT統計の取得
- JitConfigBox: JIT設定の管理（将来用）
- JitEventsBox: イベントのJSONL出力（将来用）
- JitPolicyBox: 実行ポリシー管理（将来用）

CLI拡張:
- --jit-exec, --jit-stats, --jit-dump等のフラグ追加
- --jit-directモードでの独立JIT実行
- NYASH_JIT_*環境変数によるきめ細かい制御

ドキュメント:
- Phase 10.7実装計画の詳細化
- Phase 10.9 (ビルトインBox JIT) の計画追加
- JIT統計JSONスキーマ v1の仕様化

ChatGPT5との共同開発により、JIT基盤が大幅に強化されました。
次はPhase 10.9でビルトインBoxのJIT対応を進め、
Python統合（Phase 10.1）への道を開きます。

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

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

src/jit/abi.rs

@@ -0,0 +1,62 @@
+//! JIT minimal ABI types independent from VM internals
+
+#[derive(Debug, Clone, Copy)]
+pub enum JitValue {
+    I64(i64),
+    F64(f64),
+    Bool(bool),
+    /// Opaque handle for host objects (future use)
+    Handle(u64),
+}
+
+impl JitValue {
+    pub fn as_i64(&self) -> Option<i64> { if let JitValue::I64(v) = self { Some(*v) } else { None } }
+}
+
+/// Adapter between VMValue and JitValue — keeps JIT decoupled from VM internals
+pub mod adapter {
+    use super::JitValue;
+    use crate::backend::vm::VMValue;
+
+    pub fn to_jit_values(args: &[VMValue]) -> Vec<JitValue> {
+        args.iter().map(|v| match v {
+            VMValue::Integer(i) => JitValue::I64(*i),
+            VMValue::Float(f) => JitValue::F64(*f),
+            VMValue::Bool(b) => JitValue::Bool(*b),
+            VMValue::BoxRef(arc) => {
+                let h = crate::jit::rt::handles::to_handle(arc.clone());
+                JitValue::Handle(h)
+            }
+            // For now, map others to handle via boxing where reasonable
+            VMValue::String(s) => {
+                let bx = Box::new(crate::box_trait::StringBox::new(s));
+                let bx_dyn: Box<dyn crate::box_trait::NyashBox> = bx;
+                let arc: std::sync::Arc<dyn crate::box_trait::NyashBox> = std::sync::Arc::from(bx_dyn);
+                let h = crate::jit::rt::handles::to_handle(arc);
+                JitValue::Handle(h)
+            }
+            VMValue::Void => JitValue::Handle(0),
+            VMValue::Future(f) => {
+                let bx_dyn: Box<dyn crate::box_trait::NyashBox> = Box::new(f.clone());
+                let arc: std::sync::Arc<dyn crate::box_trait::NyashBox> = std::sync::Arc::from(bx_dyn);
+                let h = crate::jit::rt::handles::to_handle(arc);
+                JitValue::Handle(h)
+            }
+        }).collect()
+    }
+
+    pub fn from_jit_value(v: JitValue) -> VMValue {
+        match v {
+            JitValue::I64(i) => VMValue::Integer(i),
+            JitValue::F64(f) => VMValue::Float(f),
+            JitValue::Bool(b) => VMValue::Bool(b),
+            JitValue::Handle(h) => {
+                if let Some(arc) = crate::jit::rt::handles::get(h) {
+                    VMValue::BoxRef(arc)
+                } else {
+                    VMValue::Void
+                }
+            }
+        }
+    }
+}