Fix/refactoring

[CodingInAVan]

Description

Refactors client startup and trace-launch planning into focused modules without changing behavior.

• Adds ClientStartup to coordinate configuration, runtime/session setup, monitor startup, collectors, segmentation, and sampling.
• Extracts startup configuration, monitor configuration, and session bootstrap logic from gpufl.cpp.
• Extracts launcher trace-run planning into TraceRunPlan.
• Adds focused unit coverage for each new module.

Type of Change

• Bug fix
• New feature
• Documentation update
• Refactoring

Testing

Checklist

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas