Add o2-sim-geometry-doctor, a geometry against field audit

[sawenzel]

This commit provides a new tool o2-sim-geometry-doctor that reads a placed geometry and a magnetic field and reports where the two do not fit together: logical volumes placed both inside and outside the field, mothers whose own material straddles the boundary, daughter clusters that would need a container of their own, and media asking for straight-line transport while sitting in real field.

The tool was motivated from the idea to check the consistency of geometry and Geant4 media properties against the properties of the magnetic field, and to potentially optimize this assignment in a second step. It is related to these O2 JIRA tickets:

https://its.cern.ch/jira/browse/O2-174
https://its.cern.ch/jira/browse/O2-175
https://its.cern.ch/jira/browse/O2-181

In the future it can be extended to provide automatic repair PRs.

It:

• builds an outer bound on the field support per threshold, phi sampled by arc length and every threshold crossing bisected, and checks the bound against the field before using it
• concludes field-free from geometry only; sampling is used only to disprove
• takes placement extents from the shapes, testing TGeoEltu before TGeoTube
• verifies a field read from a file against stored reference vectors and repairs the polarity inversion re-initialisation introduces
• reads the ifield and sensitivity flags from the geometry file itself, so it links no detector code and no simulation engine
• ships the ALICE anchor verdicts for --verify-anchors

Example:

o2-sim-geometry-doctor --geometry-file o2sim_geometry.root --field-current -5

writes geometry-doctor-proposals.json (findings with suggested actions), geometry-doctor-placements.csv (one classified row per placement) and geometry-doctor-report.txt, and prints the report.

[alibuild]

Error while checking build/O2/fullCI_slc9 for 4a455a8 at 2026-08-17 08:56:

## sw/BUILD/o2codechecker-latest/log
100% tests passed, 0 tests failed out of 1


## sw/BUILD/ThePEG-latest/log
collect2: error: ld returned 1 exit status


## sw/BUILD/O2Physics-latest/log
c++: fatal error: Killed signal terminated program cc1plus
c++: fatal error: Killed signal terminated program cc1plus
ninja: build stopped: subcommand failed.

Full log here.