Fix Hensen Open-Data Pipeline and CHSH Validation

[divyang4481]

The Hensen dataset adapter was previously using incorrect column mappings and lacked the necessary heralding filters, leading to an unphysical S-statistic and incorrect trial counts. I have updated xtheta/data/adapters/hensen.py to implement the official filtering logic described in the 2015 Nature paper. This includes:

• Applying event_ready window filters and channel coincidence checks.
• Implementing signal integrity filters (invalid markers and post-excitation clicks).
• Mapping CHSH settings to the correct random number columns.
• Deriving outcomes from readout window timing.

These changes result in a valid Bell-test dataset of 245 trials with S ≈ 2.4225, matching the published Delft results. I also updated the validation outputs in xtheta-lab/outputs/.

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PR created automatically by Jules for task 2779392400303516599 started by @divyang4481

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