Fix CaloHitSelector pseudo TOF correction and RealisticCaloReco cellID truncation

[trholmes]

This fixes two small but consequential issues found while auditing the calorimeter
timing cuts of the MAIA reconstruction chain (simhit-level timing study, validated
against chain re-runs in the mucoll-sim-ubuntu24:v3.0 stack).

1. CaloHitSelector: remove the pseudo time-of-flight correction

k4Reco/BIBUtils/src/CaloHitSelector.cpp subtracted r / TMath::C() from the hit
time before applying the time window. Two problems compound there:

• The hit time stored by RealisticCaloDigi (with timingCorrectForPropagation)
  is already corrected for the time of flight from the IP — it is the earliest
  accepted contribution's corrected time — so subtracting a TOF again would
  double-count it.
• The subtracted term mixes units: r is in mm while TMath::C() is in m/s, so
  it actually evaluates to ~7×10⁻⁶ ns instead of the ~6 ns a real TOF would be —
  a numerical no-op that made the double correction invisible.

The two bugs cancel, which is exactly why this is worth fixing: if someone later
"fixes" the units alone, the selector silently starts double-correcting and the
time window moves by the full TOF. This PR removes the term and documents that the
input time is already TOF-corrected, cutting on hit.getTime() directly.

2. RealisticCaloReco: keep the full 64-bit cellID

k4Reco/CaloDigi/src/RealisticCaloReco.cc had int cellid = hit->getCellID(),
truncating the 64-bit cellID to 32 bits before writing it to the output hit. With
cellID encodings that use the upper word — e.g. the MAIA calorimeter encoding
system:0:5,side:5:-2,module:7:8,stave:15:4,layer:19:9,submodule:28:4,x:32:-16,y:48:-16
— every reconstructed (and downstream Coned/Sel) calorimeter hit loses its x/y
cell indices, and hits from different cells become indistinguishable by cellID.
Fixed by using std::uint64_t.

Validation: outputs are unchanged (except the intended cellID repair)

Rebuilt this branch inside ghcr.io/muoncollidersoft/mucoll-sim-ubuntu24:v3.0 and
re-ran the full MAIAConfig digi+reco chain (no BIB, same seeds) on two 100-event
MAIA_v0 samples, comparing every calorimeter hit collection (Digi/Rec/Coned/Sel ×
ECAL/HCAL × barrel/endcap: cellID, energy, time, hit-by-hit) and all Pandora
cluster/PFO energies against the unpatched code:

• 50 GeV photon gun (θ = 90°): bit-identical everywhere — same hits, energies
  and times to the last bit, identical Pandora clusters/PFOs. Rec/Coned/Sel
  cellIDs now carry the full 64 bits (their 32-bit truncation equals the old
  values, and they match the digitized hits' cellIDs).
• 10 GeV π⁻ gun (θ = 90°): identical except 2 hits out of ~19,000 selected,
  each sitting within the removed ~7×10⁻⁶ ns pseudo-term of the +0.3 ns selector
  edge (t = 0.300007 and 0.300003 ns). The old code kept them by accident; the
  fixed code correctly rejects them (t ≥ TimeWindowMax). Knock-on effect: one
  Pandora cluster shifts by 0.17 GeV in each of those two events; everything else
  is bit-identical.

So behavior is preserved to float precision by construction, and the only decision
changes are hits within ~10⁻⁵ ns of the window edge, where the new behavior is the
correct one.

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