fix: Improve set_port validation

[mertcanaltin]

• Added logic to remove non-digit characters from the trimmed string using std::find_if_not and erase.
• Ensures only numeric values are processed as the port.
• Fixes cases where inputs like "8080stuff" or "8080/path" would previously cause issues, now correctly handling them as "8080".

Example:

• Input: "8080stuff" → Processed as: "8080"
• Input: "invalid80" → Processed as: "" (invalid)

Fixes #826

[anonrig]

I think we should remove the extra code right now and just focus on simplifying the code

[mertcanaltin]

I think we should remove the extra code right now and just focus on simplifying the code

thank you very much for the suggestions, I have accepted improvements that remove excess code, they have been instructive for me