docs(phase93): Phase 93 P0完了記録 & ドキュメント整理

## 追加
- docs/development/current/main/phases/phase-93/README.md
  - Phase 93 P0 (ConditionOnly Derived Slot) 完了記録
  - 実装内容・テスト結果の詳細

## 更新
- CURRENT_TASK.md: Phase 93 P0完了に伴う更新
- 10-Now.md: 現在の進捗状況更新
- 30-Backlog.md: Phase 92/93関連タスク整理
- phase-91/92関連ドキュメント: historical化・要約化

## 削減
- 735行削減（historical化により詳細をREADMEに集約）

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

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

docs/development/current/main/design/joinir-design-map.md

@@ -106,6 +106,7 @@ flowchart LR
 - Trace（JoinIR ルートの統一トレース）: [`src/mir/builder/control_flow/joinir/trace.rs`](../../../../../src/mir/builder/control_flow/joinir/trace.rs)
 - Error tags（SSOT）: [`src/mir/join_ir/lowering/error_tags.rs`](../../../../../src/mir/join_ir/lowering/error_tags.rs)
 - Loop Canonicalizer（前処理 SSOT）: [`src/mir/loop_canonicalizer/mod.rs`](../../../../../src/mir/loop_canonicalizer/mod.rs)
+- ConditionOnly Derived Slot（Phase 93）: [`src/mir/join_ir/lowering/common/condition_only_emitter.rs`](../../../../../src/mir/join_ir/lowering/common/condition_only_emitter.rs)
 
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