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/28-sysin/README.md

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+# 28-sysin — SYSIN Reading Simulation
+
+## 电信业务场景
+
+批量参数SYSIN读取。从SYSIN文件读取月次批处理参数(账期、报表类型、输出格式等)，控制批处理行为。
+
+## Purpose
+Demonstrates reading parameter cards from a SYSIN file (LINE SEQUENTIAL) in PARAM=VALUE format and using them to control program behavior.
+
+## Test Coverage
+1. **Normal parameters** — Read SORT-KEY, OUTPUT-FMT, MAX-RECORDS, etc.
+2. **Multi-card reading** — Process multiple parameter cards sequentially
+3. **Comments** — Lines starting with * or # are skipped
+4. **Empty SYSIN** — File with no content uses defaults
+5. **Format errors** — Missing '=', malformed cards are detected and counted
+6. **Default values** — Parameters not specified retain their defaults
+
+## Key Techniques
+- LINE SEQUENTIAL file ORGANIZATION for SYSIN
+- FUNCTION TRIM for whitespace handling
+- FUNCTION UPPER-CASE for case-insensitive matching
+- EVALUATE for parameter dispatch
+- FILE STATUS checking (10 = end of file)