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>

data/__init__.py

@@ -1,3 +1,29 @@
+"""COBOL 数据模型 — 所有模块共享的契约
+
+本包定义了全系统共用的数据类。所有模块的输入/输出必须使用这些类。
+修改本包需通知所有开发者。
+
+导入方式:
+  from data import Field, FieldTree             # 字段树
+  from data import TestCase, TestSuite, SparkConfig  # 测试数据
+  from data import FieldResult, VerificationRun  # 对比结果
+"""
+
+from __future__ import annotations
+
 from .field_tree import Field, FieldTree
 from .test_case import TestCase, TestSuite, SparkConfig
 from .diff_result import FieldResult, VerificationRun
+
+__all__ = [
+    # ═══ 字段树 ── cobol_testgen / comparator / agents 共用 ═══
+    "Field",             # dataclass — 单个字段定义
+    "FieldTree",         # dataclass — COPYBOOK 字段树
+    # ═══ 测试数据 ── cobol_testgen / runners 共用 ═══
+    "TestCase",          # dataclass — 单条测试用例
+    "TestSuite",         # dataclass — 测试套件（含 Spark 配置）
+    "SparkConfig",       # dataclass — Spark 运行参数
+    # ═══ 对比结果 ── comparator / report / orchestrator 共用 ═══
+    "FieldResult",       # dataclass — 单个字段对比结果
+    "VerificationRun",   # dataclass — 管道运行全结果
+]