fix: gcov Windows本地化 + runner合并 + 决策覆盖率修复

- gcov从WSL 15.2改为Windows MinGW 9.2.0，消除.gcno格式不匹配
- coverage.py去除leaf_stats复位bug（决策覆盖率恢复）
- runner.py合并V3编译+SOURCE分组执行+出力保存
- __init__.py gcov条件/outdir解析修复

cobol_testgen/core.py

@@ -1402,15 +1402,22 @@ def propagate_assignments(rec, assignments, fields, file_sec=None):
         if pi.get('type') == 'numeric':
             digits = pi.get('digits', 0)
             decimal = pi.get('decimal', 0)
-            total = digits + decimal
             s = str(val)
             neg = s.startswith('-')
             if neg:
                 s = s[1:]
-            s = s.zfill(total)
-            int_part = s[:digits] if digits else '0'
-            dec_part = s[digits:] if decimal > 0 else '0'
-            result = float(int(int_part or '0') + int(dec_part or '0') / (10 ** decimal))
+            # Handle explicit decimal point (e.g. "008." or "12.34")
+            if '.' in s:
+                parts = s.split('.')
+                int_part = parts[0]
+                dec_part = parts[1] if len(parts) > 1 else ''
+            else:
+                total = digits + decimal
+                s = s.zfill(total)
+                int_part = s[:digits] if digits else '0'
+                dec_part = s[digits:] if decimal > 0 else ''
+            dec_val = int(dec_part.ljust(decimal, '0')[:decimal] or '0') if decimal > 0 else 0
+            result = float(int(int_part or '0') + dec_val / (10 ** decimal))
             return -result if neg else result
         try:
             return float(val)