docs(phase 104): .hako側ロギング設計ガイド確立

- Add Section 4 (.hako側ロギング方針) to logging_policy.md
- Create hako_logging_design.md (comprehensive guide, 331 lines)
- Define 4 logging categories (user-facing/dev-debug/monitoring/internal Rust)
- Provide 3 logging box patterns (Lightweight/Structured/Contextual)
- Add best practices and anti-patterns with code examples
- Update ring0-inventory.md with Phase 104 entry
- Cross-reference documentation for consistency

This completes Phase 104: establishing user-facing logging guidelines
for Nyash applications, complementing Rust-side logging policy from
Phase 99-101.

Files modified:
- docs/development/current/main/logging_policy.md
- docs/development/current/main/hako_logging_design.md (new)
- docs/development/current/main/ring0-inventory.md

Related: Phase 99 (logging policy design), Phase 100-101 (Rust impl)

docs/development/current/main/ring0-inventory.md

@@ -326,6 +326,20 @@ ring0.log.debug(&format!("Operation completed in {}ms", duration));
 **Other**: ~277 locations
 - TBD
 
+### Phase 104: .hako側ロギング設計 (COMPLETED)
+
+**Scope**:
+- ConsoleBox適切な使い方ガイド
+- ユーザー定義Boxからのロギングベストプラクティス
+- 4つのロギングカテゴリ確立（user-facing/dev-debug/monitoring/internal Rust）
+- 3つのロギングBoxパターン（Lightweight/Structured/Contextual）
+
+**Files Created/Updated**:
+- docs/development/current/main/logging_policy.md (Section 4 追加)
+- docs/development/current/main/hako_logging_design.md (new)
+
+**Status**: Complete - .hako側ロギング設計確立
+
 ---
 
 ## Section 5: Migration Roadmap