Update charm and beauty lifetimes in the Pythia8 decay base config

This commit updates the tau0 of eight weakly decaying charm and beauty hadrons in base.cfg to the PDG 2026 values.

- Xi_c+ (4232): 0.132 -> 0.1358 mm.
- Xi_c0 (4132): 0.0336 -> 0.04497 mm.
- Omega_c0 (4332): 0.021 -> 0.08214 mm.
- B_s0 (531): 0.439 -> 0.4542 mm, from the mean life 1/Gamma_s.
- B_c+ (541): 0.138 -> 0.1529 mm.
- Xi_b- (5132): 0.364 -> 0.4707 mm.
- Xi_b0 (5232): 0.364 -> 0.4413 mm.
- Omega_b- (5332): 0.364 -> 0.4917 mm.
- Xi_c0 and Omega_c0 now differ from Geant4 by 1.3% and 2.2%, so the event decayer lists them in its lifetime report.
- DecayerPythia8 reads the same file, but Geant4 takes only the momenta of the external decayer's products and places them at its own decay point (TG4ExtDecayer, G4Decay), so decays during transport do not change.

https://pdglive.lbl.gov/Particle.action?init=0&node=S045
https://pdglive.lbl.gov/Particle.action?init=0&node=S048
https://pdglive.lbl.gov/Particle.action?init=0&node=S047
https://pdglive.lbl.gov/Particle.action?init=0&node=S086
https://pdglive.lbl.gov/Particle.action?init=0&node=S091
https://pdglive.lbl.gov/Particle.action?init=0&node=S069
https://pdglive.lbl.gov/Particle.action?init=0&node=S070
https://pdglive.lbl.gov/Particle.action?init=0&node=S063
https://its.cern.ch/jira/browse/O2-5903

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Author: sawenzel

Generators/share/pythia8/decays/base.cfg

@@ -32,3 +32,14 @@ Init:showChangedParticleData off
 4232:mayDecay off	# Xi_c+
 4332:mayDecay off	# Omega_c0
 5122:mayDecay off	# Lambda_b0
+
+### lifetimes (PDG 2026), Pythia defaults are older measurements
+
+531:tau0  = 0.4542	# B_s0
+541:tau0  = 0.1529	# B_c+
+4132:tau0 = 0.04497	# Xi_c0
+4232:tau0 = 0.1358	# Xi_c+
+4332:tau0 = 0.08214	# Omega_c0
+5132:tau0 = 0.4707	# Xi_b-
+5232:tau0 = 0.4413	# Xi_b0
+5332:tau0 = 0.4917	# Omega_b-