refactor: Fix get_unix_timestamp return type to use standard time_t

[Lang-Qiu]

问题背景

The function get_unix_timestamp() previously declared its return type as long int, but it returns the result of the standard time(NULL) function, which returns time_t. While these types might be the same on many common platforms (like Linux), time_t is the portable and correct type as specified by the C standard. Using long int could lead to compilation warnings or errors on platforms where time_t is defined differently.

修改内容

• 修改了什么: Changed the return type of the get_unix_timestamp() function from long int to time_t.
• 为什么这样改: This aligns the function signature with the standard return type of time(), ensuring code correctness and portability across different platforms and compilers.
• 对代码质量/性能/安全性的提升: 代码质量/可移植性提升: Eliminates a potential source of non-portable code and compiler warnings. The change is purely a type correction and has zero impact on runtime behavior or performance.

验证方式

• 是否通过了现有测试: This change is a simple type correction. All existing tests that use this function should continue to pass, as the returned value's bit pattern is unchanged.
• 是否添加了新的测试: No new tests are required, as the change does not alter any functionality.
• 是否进行了手动验证: Verified that the code compiles correctly with the updated type.

其他信息

• 是否有 breaking changes: 理论上 yes, 实践上 no. The function's public signature is changed. However, time_t is typically defined as a long or long int on most UNIX-like systems. Code calling this function and assigning the result to a long int variable will still work, possibly with an implicit conversion or a minor warning on some compilers. It is a breaking change in the strictest sense, but it is a necessary correction for portability.
• 是否需要更新文档: No. The function's behavior and purpose are unchanged.
• 是否有已知的限制: None.

[h-filali]

We are closing this PR as the proposed changes do not align with our current development priorities, address any tracked issues, or meet our required technical standards.