Optimize build performance and separate linting from compilation [PRIORITY]

[samueleternity]

Problem

The CI/CD lint job takes 23+ minutes to complete, primarily due to two issues:
Source File Duplication in CMake

The same source files are compiled multiple times across different targets:

Main executable compiles files once 
Each test executable recompiles the same service files (6 tests × duplication)
Benchmark executable recompiles the same files again

Files to fix:
CMakeLists.txt - Add moderation_core library
tests/CMakeLists.txt - Use moderation_core library
benchmark/CMakeLists.txt - Use moderation_core library

Additionally check the binary caching of Conan2