Migrate CHARLIE runtime activation from Conda strings to Mamba-safe environment setup

[kopardev]

Summary

CHARLIE runtime scripts still relied on Conda-style activation patterns and wrapper behavior that caused noisy or fragile execution. We migrated runtime activation to a Mamba-first flow and removed Conda activation references from targeted entrypoints.

Scope

• Update runtime activation construction in charlie
• Keep cluster-specific module loading behavior
• Ensure activation command is reused in generated slurm submit script path
• Simplify wrapper dispatch behavior in bin/redirect
• Remove CONDA_PREFIX usage in CHARLIE runtime in favor of MAMBA_PREFIX

Acceptance

• charlie --help has no shell-init/libmamba warnings
• charlie -m=dryrun no longer fails on old Conda activation path errors
• No conda activate / conda.sh refs in targeted runtime files