Security: Multiple Insecure fprintf() Usage

[smooge]

Priority: HIGH
File: Src/checkX.c
Function: checkout()
Discovered: During clang-tidy static analysis testing

Description: Multiple calls to fprintf() without bounds checking or security validation. clang-tidy identifies these as security risks that should use safer alternatives with length arguments or boundary checks.

Reproduction Steps:

1. Run clang-tidy Src/checkX.c -checks=clang-analyzer-security*
2. Multiple warnings about insecure fprintf() usage at lines 128, 135, 144, 150, 158
3. Expected: Use fprintf_s() or similar bounded alternatives

Impact: Potential buffer overflow vulnerabilities in logging and output functions. Could be exploited if format strings are controlled by user input.

Proposed Fix: Replace fprintf() calls with safer alternatives:

/* Before (insecure) */
fprintf(fupdate, "%s[%d]: %s has repro > 15 of %d\n", ...);

/* After (secure) */
snprintf(buffer, sizeof(buffer), "%s[%d]: %s has repro > 15 of %d\n", ...);
fprintf(fupdate, "%s", buffer);
/* OR use fprintf_s if available */

Original Bug ID: BUG-004