feat: Phase 2 complete — 13 Phases of COBOL type classification and test benchmark

P0.6: gcov infrastructure
P1: extract_structure output expansion (11 new feature fields)
P2: Confusion group rule engine (8 pairs + contradiction + backtrack)
P3: 4-factor confidence calculation + quality gate update
P4: 33+2 COBOL program type test samples (22 files, 7 categories)
P5: parametrized/ test data generation engine
P6: japanese_data.py lookup tables
P7-10: Type-specific test suites (~159 parametrized tests)
P11: Full classification pipeline (classify_program) + orchestrator integration
P12: Documentation (module-interfaces, test-plan v3.0, coverage-matrix)

Architecture decisions:
- classification_pipeline/ merged to hina/pipeline/
- parametrized/ as independent module
- japanese_data.py as root-level file
- hina/__all__ only exports classify_program()

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

storage/__init__.py

@@ -1 +1,18 @@
+"""存储层包
+
+公开 API:
+  DiskCache        — 磁盘缓存（SHA256 key → JSON）
+  ReportStore      — 报告历史存储（JSONL）
+  TestDataBundle   — 测试数据文件路径管理
+"""
+
+from __future__ import annotations
+
+from .store import DiskCache, ReportStore
 from .bundle import TestDataBundle
+
+__all__ = [
+    "DiskCache",        # class
+    "ReportStore",      # class
+    "TestDataBundle",   # class
+]