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/06-branch-evaluate/README.md

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+# 06-branch-evaluate — EVALUATE Branch Program
+
+## 电信业务场景
+
+套餐类型判定。根据套餐代码(P01/P02/P03)进行EVALUATE分支，按套餐类型分流处理。
+
+Demonstrates GnuCOBOL EVALUATE patterns:
+
+- **EVALUATE with ALSO**: Two-condition EVALUATE on KEY and DATA2
+- **EVALUATE TRUE/FALSE**: Evaluate boolean conditions
+- **EVALUATE multi-value WHEN**: Multiple WHEN values for same action
+- **WHEN OTHER**: Default/catch-all branch
+
+## Files
+
+| File | Purpose |
+|------|---------|
+| `main-06-branch-evaluate.cbl` | COBOL program (fixed format) |
+| `data-gen.sh` | Generate test data |
+| `run.sh` | Compile, run, verify outputs |
+
+## Input Record
+
+Same as 05-branch-if: KEY(10) + DATA1(20) + DATA2(10)
+
+## Branch Logic
+
+| KEY Value | Output File |
+|-----------|-------------|
+| 'A' | FILE-A.DAT |
+| 'B' | FILE-B.DAT |
+| 'C' | FILE-C.DAT |
+| any other | FILE-OTHER.DAT |