feat: add benchmark-programs — 58 telecom COBOL test programs

作为子目录纳入系统，与核心测试管道协同

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

benchmark-programs/35-merge/README.md

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+# 35-merge — MERGE Processing Program
+
+## 电信业务场景
+
+多源CDR合并。使用MERGE语句将来自多个BSS系统的CDR文件(2~3个)合并为一个统合CDR文件，支持OUTPUT PROCEDURE。
+
+## Purpose
+Demonstrates COBOL MERGE statement capabilities, covering MR-N001 through MR-N004 and MR-A001.
+
+## Test Coverage
+| ID | Test | Description |
+|----|------|-------------|
+| MR-N001 | 2-file MERGE | Merge two sorted files, ASCENDING KEY |
+| MR-N002 | 3-file MERGE | Merge three sorted files into one |
+| MR-N003 | Duplicate key MERGE | Files with overlapping keys |
+| MR-N004 | OUTPUT PROCEDURE | MERGE with output procedure processing |
+| MR-A001 | Unsorted input anomaly | MERGE with unsorted input (expected unpredictable results) |
+
+## Key Techniques
+- MERGE USING (multiple input files)
+- MERGE GIVING (direct output)
+- MERGE with OUTPUT PROCEDURE
+- RETURN statement in output procedure
+- ASCENDING KEY for merge ordering
+- Note: MERGE requires pre-sorted input files