Initialize hangs in pyDEME after solver setup on WSL (CUDA Blackwell/compute_120)

[박선호]

## Environment
- OS: Windows + WSL Ubuntu
- GPU: NVIDIA Blackwell class GPU (compute_120)
- CUDA: tested with 12.8 (also checked arch override)
- DEME: pyDEME 2.3.3 (`pip install DEME`)
- Python: conda env, Python 3.11
- Note: similar behavior observed in both pyDEME path and C++ demo path during initialization-stage runs in our setup history.

## Problem
The simulation hangs right after solver setup and never reaches Initialize completion.
In our marker logs, execution reaches setup marker (e.g., `P3_SETUP`) but does not reach initialize marker (e.g., `P4_INIT`).

## Reproduction
1. Create clean conda env (Python 3.11)
2. Install DEME via pip
3. Run a minimal script that:
   - imports DEME
   - creates `DEMSolver`
   - sets basic material/scene
   - calls `Initialize`
4. Observe process stalls indefinitely after setup stage

## Expected
`Initialize` should complete and proceed to timestep loop or first output frame.

## Actual
Process stalls/hangs after setup stage with no forward progress.

## What we already tried
- Clean reinstall of DEME and environment
- Re-run with persistent JIT cache related env vars
- Set `DEME_DEFAULT_CUDA_ARCH=compute_120`
- Cross-check with C++ path and minimal demos
- Investigated known jitify/startup related PRs/issues history

## Questions
- Is Blackwell/compute_120 fully validated for current pyDEME path?
- Are there recommended flags/env vars for avoiding Initialize-stage stalls?
- Any known incompatibility matrix for CUDA/GCC/driver combinations specific to pyDEME?

[Ruochun Zhang]

Thanks for reporting this. To answer your question, newer CUDA and newer GPUs are indeed less tested. But I just tested the C++ version of DEME on a 5090 machine with CUDA=12.8, and it works fine for me (did not test pyDEME yet). So there are incompatible setups, but CUDA 12.8 and the newest NV driver are not among them.

So please help me understand: Are you saying that for both your pyDEME installation and the compiled-from-source C++ version, you got the stalling problem at demo initialization? And your CUDA version is 12.8 (not 13.0+)? And if you are willing to spend a bit more time on it, could you try debugging it and let me know if it stalls at the just-in-time compilation (i.e., spending 20 minutes or so just to compile one kernel)?

There are plans to modernize the pyDEME installation process, and DEME itself, which may be online quite soon, which I hope will resolve potential problems, at least to better show where the stalling happens.

Thank you,

Ruochun