Fix socket attenuator issues

[wptestyyh]

Type

• Bug fix
• Feature addition
• [] Feature update
• Documentation
• Build Infrastructure

Side Effects

• Breaking change
• Non-functional change

Goals

This change fixes below issues that is found when testing against AFW83 attenuator.

• select first parameter is not optional on Linux, it must be the socket descriptor+1
• select will change the timeout parameter, so it cannot be reused and must be reinitialized
• CLI single dash switch (-) can only be followed by a single character

Technical Details

• None

Test Results

• Test it works with AFW83
  ./rfattenuator-cli socket "AFW83" 192.168.3.137 10001
  Sanity check succeeded

Reviewer Focus

• None

Future Work

• Stablization

Checklist

• Build target all compiles cleanly.
• clang-format and clang-tidy deltas produced no new output.
• Newly added functions include doxygen-style comment block.