Phase 74-1/74-2: UnifiedCache LOCALIZE optimization (P1 frozen, NEUTRAL -0.87%)

Phase 74-1 (ENV-gated LOCALIZE):
- Result: +0.50% (NEUTRAL)
- Runtime branch overhead caused instructions/branches to increase
- Diagnosed: Branch tax dominates intended optimization

Phase 74-2 (compile-time LOCALIZE):
- Result: -0.87% (NEUTRAL, P1 frozen)
- Removed runtime branch → instructions -0.6%, branches -2.3% ✓
- But cache-misses +86% (register pressure/spill) → net loss
- Conclusion: LOCALIZE本体 works, but fragile to cache effects

Key finding:
- Dependency chain reduction (LOCALIZE) has low ROI due to cache-miss sensitivity
- P1 (LOCALIZE) frozen at default OFF
- Next: Phase 74-3 (P0: FASTAPI) - move branches outside hot loop

Files:
- core/hakmem_build_flags.h: HAKMEM_TINY_UC_LOCALIZE_COMPILED flag
- core/box/tiny_unified_cache_hitpath_env_box.h: ENV gate (frozen)
- core/front/tiny_unified_cache.h: compile-time #if blocks
- docs/analysis/PHASE74_*: Design, instructions, results
- CURRENT_TASK.md: P1 frozen, P0 next instructions

Also includes:
- Phase 69 refill tuning results (archived docs)
- PERFORMANCE_TARGETS_SCORECARD.md: Phase 69 baseline update
- PHASE70_REFILL_OBSERVABILITY_PREREQS_SSOT.md: Route banner docs

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

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

docs/analysis/PERFORMANCE_TARGETS_SCORECARD.md

@@ -11,7 +11,7 @@
 
 mimalloc との比較は **FAST build** で行う（Standard は fixed tax を含むため公平でない）。
 
-## Current snapshot（2025-12-17, Phase 68 PGO — 新 baseline）
+## Current snapshot（2025-12-18, Phase 69 PGO + WarmPool=16 — 現行 baseline）
 
 計測条件（再現の正）：
 - Mixed: `scripts/run_mixed_10_cleanenv.sh`（`ITERS=20000000 WS=400`）