Fix LF resonance gap injection and Add phi meson configuration

[mjkim525]

This PR fixes the gap-injection logic in the PWGLF resonance generator and adds the (\phi(1020)) dielectron channel to the resonance injection configuration.

Changes

• Fix the handling of minimum-bias events between injected signal events.

  • Previously, gap events could return before their particles were imported.
  • This resulted in an empty event being passed to o2-sim, which could cause the event to be retried instead of preserving the intended minimum-bias event.
  • The generated minimum-bias event is now always imported, while injected particles are appended only for signal events.

• Use a single signal-event decision for both the injection and triggering paths.

  • gap = N, with N > 1: generate signals at events (0, N, 2N ...), with minimum-bias events in between.

• Register and propagate the event class through MCEventHeader::subGeneratorId.

  • 0: minimum-bias event
  • 1: signal event

  This information is available in the analysis through mcCollision.getSubGeneratorId().

• Add (\phi(1020)) to resonancelistgun_width_inj.json.

[github-actions]

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