feat: config-driven multi-scenario + gcda accumulation fix + gcov merge fix

Config-driven architecture:
- coverage_dates: YAML-driven date replacement for LEAVE_RECORDS
- row_overrides: per-scenario field overrides (e.g. STATUS='9')
- delete_all_rows: per-scenario table emptying for empty-cursor tests

gcda accumulation fix (V3 bug #7):
- Delete .gcda before each scenario run to prevent GnuCOBOL accumulation
- Force-copy scenario gcda (skip mtime check)
- Copy scenario DB to CWD data/kin.db for CONNECT TO path resolution

Multi-run gcov merge fix:
- Always merge multi-run gcov data regardless of generate_coverage flag
- Fix v3_root UnboundLocalError in cleanup path

Other fixes:
- _make_key_unique: skip WHERE-constrained columns to avoid PK conflict
- incremental_supplement: support fields_dict for base record generation
- check_coverage: use structure coverage data if available
- orchestrator.py: filter _-prefixed fields in TestCase; merge Agent2Data cases

cobol_testgen/__init__.py

@@ -28,7 +28,7 @@ from .core import build_branch_tree, classify_field_roles, _init_child_names, sq
 from .cond import parse_single_condition, is_field, collect_leaves
 from .pipeline_bridge import build_branch_tree_fallback
 from .design_mcdc import enum_paths as mcdc_enum_paths, _filter_stop
-from .design import enum_paths, generate_records, get_term_type, extend_abend_programs
+from .design import enum_paths, generate_records, get_term_type, extend_abend_programs, make_base_record
 from .output import output_json, output_input_files
 from .coverage import run_coverage, generate_coverage_index, collect_decision_points, mark_coverage
 from japanese_data import generate_fullwidth_text, generate_halfwidth_katakana, generate_wareki_date
@@ -1195,6 +1195,7 @@ def extract_structure(cobol_source: str, copybook_dirs: list = None) -> dict:
         "if_types": if_types,
         "variable_patterns": variable_patterns,
         "open_pattern": open_pattern,
+        "data_fields": fields_dict,
     }
 
 
@@ -1353,12 +1354,13 @@ def generate_data(cobol_source: str, structure: dict = None,
     return records
 
 
-def incremental_supplement(branch_tree, decision_gaps: list[int]) -> list[dict]:
+def incremental_supplement(branch_tree, decision_gaps: list[int], fields_dict: list = None) -> list[dict]:
     """针对未覆盖的决策点，增量生成补充测试数据。
 
     Args:
         branch_tree: extract_structure() 返回的 branch_tree 字段
         decision_gaps: 未覆盖的决策点 ID 列表，如 [1, 3, 5]
+        fields_dict: 字段定义列表（DATA DIVISION 展开后），提供后生成含字段值的记录
 
     Returns:
         list[dict]: 增量测试数据，格式与 generate_data() 兼容
@@ -1390,10 +1392,12 @@ def incremental_supplement(branch_tree, decision_gaps: list[int]) -> list[dict]:
 
     supplements = []
     for i, (kind, label) in enumerate(found):
-        supplements.append({
-            "_dec_id": f"incr_{i}",
-            "_kind": kind,
-            "_label": str(label)[:60],
-        })
+        rec = {}
+        if fields_dict:
+            rec = make_base_record(i + 1, fields_dict)
+        rec["_dec_id"] = f"incr_{i}"
+        rec["_kind"] = kind
+        rec["_label"] = str(label)[:60]
+        supplements.append(rec)
 
     return supplements