[PWGCF] Femto: Add D0 meson support to the femto framework

[IgorPtak]

Adds D0 mesons as a new particle species to the unified femto framework, enabling D0-hadron femtoscopic correlations.

What is added

Data model - three new tables:

• FD0s - kinematics, mass of the accepted hypothesis and daughter indices
• FD0Masks - selection bitmask
• FD0Extras - QA/debug: both mass hypotheses, topological variables, BDT scores and the PWGHF selection flags
• FD0Labels - MC labels

Core: charmHadronBuilder.h and charmHadronHistManager.h, following the structure of the existing V0/cascade builders. D0 candidates are taken from PWGHF (HfCand2Prong), with the acceptance applied as a rapidity cut via HfHelper. The D0/D0bar hypothesis is encoded in the sign of the stored signed pT.

Tasks: two new workflows:

• femto-d0-qa - QA for D0 candidates and their daughters
• femto-pair-track-d0 - D0-hadron correlations, same and mixed event

MC: D0 candidates have no direct MC label, so both prongs are matched to a generated D0 -> K pi decay with RecoDecay::getMatchedMCRec. Charm hadrons are additionally classified as prompt or non-prompt, which required extending the McOrigin enum.

[github-actions]

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