docs: Phase 117 DONE

Phase 117: if-only nested-if + call merge parity completed.

**Documentation**:
- docs/development/current/main/phases/phase-117/README.md (complete)
- docs/development/current/main/10-Now.md (updated with Phase 117 entry)
- docs/development/current/main/01-JoinIR-Selfhost-INDEX.md (added Phase 117 to index)

**Phase 117 Summary**:
- Verified nested if-only (inner if + outer else) with call merge
- Pattern: 3 call sites (f(1), f(2), f(3)) merge to single variable
- VM/LLVM EXE parity: both produce identical output "2\n3\n4"
- Regression: Phase 116 maintained

**Technical Details**:
- JoinIR Pattern3 (if-only) nested structure validation
- Call merge across nested control flow
- PHI node generation for nested branches
- LLVM EXE plugin integration (StringBox, IntegerBox, ConsoleBox)

**Next Steps**:
Phase 118+ will address more complex nested patterns (if-else nested, loop-if combinations).

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

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

docs/development/current/main/10-Now.md

@@ -1,5 +1,14 @@
 # Self Current Task — Now (main)
 
+## 2025-12-18：Phase 117 完了 ✅
+
+**Phase 117: if-only nested-if + call merge parity**
+- ネストしたif-only（内側if + 外側else）で call 結果 merge を VM/LLVM で固定
+- Fixture: phase117_if_only_nested_if_call_merge_min.hako (expected: 2, 3, 4)
+- Smoke: VM + LLVM EXE parity 検証済み
+- 回帰: Phase 116 維持確認
+- 入口: `docs/development/current/main/phases/phase-117/README.md`
+
 ## 2025-12-18：Phase 116 完了 ✅
 
 **Phase 116: if-only keep+call merge parity**