Draft: PicoCal shower studies

This MR contains two types of changes. The first part (in Sim/GaussPicoCal/) is intended for merging into Gauss once the changes have been validated.

Modifications to PicoCal in Gauss

• Updated clockTime definition in PicoCalSubHit to record timing information for the earliest step rather than the last filled step
• Added step information recording within PicoCalSubHit properties for comprehensive analysis
• Enhanced logging with detailed step-by-step information from G4Step to PicoCalHit levels

Analysis Framework for PicoCal Clustering in Gauss (PicoCal/)

• Shell scripts (run-pgun.sh, run-minbias.sh) with configurable options for particle gun and minimum bias events
• Log parsing tool (parse_picocal_simple.py) that extracts detailed step-by-step simulation data from Gauss log files using OutputLevel-3
• Analysis suite (analysis.py) providing comprehensive visualization and analysis of simulation results

The framework supports Run5 + PicoCal detector configurations and generates structured CSV outputs for further analysis. For more detailed description please see PicoCal/analysis/README.md.

This MR depends on the corresponding changes in the branch lcg-105-compat_picocal_boole of LHCb.