🎉 Phase 11.8/12.7: MIR Core-13 完全実装 + 糖衣構文ドキュメント更新

主要な変更:
- MIR Core-13命令セット確定（Load/Store削除の革命的設計）
  - Const, BinOp, Compare（値・計算）
  - Jump, Branch, Return, Phi（制御）
  - Call, BoxCall, ExternCall（呼び出し）
  - TypeOp, Safepoint, Barrier（メタ）
- Phase 12.7糖衣構文ドキュメント整理（超圧縮重視、可逆変換保証）
- MIRビルダーのモジュール分割完了
- vtableテストスイート拡充
- AI協調開発ツール追加（並列リファクタリング支援）

詳細:
- src/mir/instruction_introspection.rs: core13_instruction_names()追加
- MIRビルダー分割: decls.rs, exprs_*.rs, fields.rs
- plugin_loader_v2: errors.rs, host_bridge.rs分離
- 論文用データ: mir13-final.md作成

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

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

src/mir/builder/exprs_peek.rs

@@ -0,0 +1,50 @@
+use super::{BasicBlockId, ValueId};
+use crate::ast::{ASTNode, LiteralValue};
+
+impl super::MirBuilder {
+    // Peek expression lowering
+    pub(super) fn build_peek_expression(
+        &mut self,
+        scrutinee: ASTNode,
+        arms: Vec<(LiteralValue, ASTNode)>,
+        else_expr: ASTNode,
+    ) -> Result<ValueId, String> {
+        let scr_val = self.build_expression_impl(scrutinee)?;
+        let merge_block: BasicBlockId = self.block_gen.next();
+        let result_val = self.value_gen.next();
+        let mut phi_inputs: Vec<(BasicBlockId, ValueId)> = Vec::new();
+        let mut next_block = self.block_gen.next();
+        self.start_new_block(next_block)?;
+
+        for (i, (label, arm_expr)) in arms.iter().cloned().enumerate() {
+            let then_block = self.block_gen.next();
+            // Only string labels handled here (behavior unchanged)
+            if let LiteralValue::String(s) = label {
+                let lit_id = self.value_gen.next();
+                self.emit_instruction(super::MirInstruction::Const { dst: lit_id, value: super::ConstValue::String(s) })?;
+                let cond_id = self.value_gen.next();
+                self.emit_instruction(super::MirInstruction::Compare { dst: cond_id, op: super::CompareOp::Eq, lhs: scr_val, rhs: lit_id })?;
+                self.emit_instruction(super::MirInstruction::Branch { condition: cond_id, then_bb: then_block, else_bb: next_block })?;
+                self.start_new_block(then_block)?;
+                let then_val = self.build_expression_impl(arm_expr)?;
+                phi_inputs.push((then_block, then_val));
+                self.emit_instruction(super::MirInstruction::Jump { target: merge_block })?;
+                if i < arms.len() - 1 {
+                    let b = self.block_gen.next();
+                    self.start_new_block(b)?;
+                    next_block = b;
+                }
+            }
+        }
+
+        let else_block_id = next_block;
+        self.start_new_block(else_block_id)?;
+        let else_val = self.build_expression_impl(else_expr)?;
+        phi_inputs.push((else_block_id, else_val));
+        self.emit_instruction(super::MirInstruction::Jump { target: merge_block })?;
+        self.start_new_block(merge_block)?;
+        self.emit_instruction(super::MirInstruction::Phi { dst: result_val, inputs: phi_inputs })?;
+        Ok(result_val)
+    }
+}
+