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/10-divide-50/README.md

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+# 10-divide-50 — 50-Division File Splitter
+
+## 电信业务场景
+
+请求书50分割。将请求书数据按50件一个文件进行分割输出，用于分批印刷或批量发送。
+
+Demonstrates dividing input records into groups of 50:
+
+- **PERFORM VARYING counter**: Track record numbers across the loop
+- **DIVIDE ... GIVING REMAINDER**: Calculate file number from record count
+- **Close-write cycle**: Close old file, open new file at each boundary
+- Tested at boundary conditions: 50 (exact), 51 (one extra), 49 (one short)
+
+## Files
+
+| File | Purpose |
+|------|---------|
+| `main-10-divide-50.cbl` | COBOL program (fixed format) |
+| `data-gen.sh` | Generate N test records (default 51) |
+| `run.sh` | Compile + run 3 test cases |
+
+## Algorithm
+
+```
+DIVIDE record-count BY 50 GIVING Q REMAINDER R
+IF R = 1 → open new FILE-OUT-NN
+Write record to current file
+```
+
+## Output Files
+
+- FILE-OUT-01.DAT: records 1-50
+- FILE-OUT-02.DAT: records 51-100
+- etc.