FT0: update Digitizer signal shape and trigger logic; FV0: update trigger logic in digitizer

[spulawsk]

This PR introduces an updated signal shape model and revised trigger handling in the FT0 digitization.

The signal response used in the FT0 digitizer has been updated to a parametrization based on a sum of two log-normal components. This allows a better description of the detector pulse shape in Monte Carlo simulations and improves the agreement between simulated trigger response and data.

In addition, trigger logic has been adjusted to better reproduce the behaviour of the FT0 trigger chain.

Main changes

Signal model:

introduce a new signal shape function based on two log-normal components
provide analytical integral of the signal shape for amplitude evaluation
keep the previous implementation commented for reference

Trigger tuning:

update trigger thresholds in FT0DigParam (mtrg_central_trh, mtrg_semicentral_trh)
introduce a dedicated vertex trigger gate parameter (mTime_trg_vertex_gate)

Digitizer improvements:

introduce mapping from channel ID to PM hash using FT0 metadata
accumulate charge per PM using the mapping
improve calculation of central and semicentral triggers based on summed PM charge
add monitoring of summed PM amplitudes (debug logging)

The definition of FT0 triggers in the digitizer is updated to better match the trigger logic used in data processing. In particular, the central, semicentral, and vertex trigger conditions are now computed using PM-summed amplitudes and timing definitions consistent with those used in the FT0 trigger chain.

In addition, the FV0 trigger logic has been corrected to follow a consistent definition with the data.

These changes improve the consistency between MC digitization and the trigger quantities reconstructed from data.

No changes to the data format are introduced.

[github-actions]

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[alibuild]

Error while checking build/O2/fullCI_slc9 for 4725b5e at 2026-03-30 19:59:

## sw/BUILD/O2Physics-latest/log
c++: fatal error: Killed signal terminated program cc1plus
ninja: build stopped: subcommand failed.


## sw/BUILD/o2checkcode-latest/log
--
========== List of errors found ==========
++ GRERR=0
++ grep -v clang-diagnostic-error error-log.txt
++ grep ' error:'
++ GRERR=1
++ [[ 1 == 0 ]]
++ mkdir -p /sw/INSTALLROOT/7fbe59bf5c91181fead2b7ddb5eec307f738556e/slc9_x86-64/o2checkcode/1.0-local15/etc/modulefiles
++ cat
--

Full log here.