Particles: add escaped particle TSV output

[lwJi]

Summary

• Add out_escaped_tsv boolean parameter to capture particles leaving the domain to a cumulative ptcl_escaped.tsv file before Redistribute() destroys them
• Uses the existing sequential-barrier MPI write pattern for correct parallel output
• Enable in TestNuPcsArdBH test with reference output for regression testing

Test plan

• Build succeeds (./agent_scripts/build.sh)
• All tests pass including new reference output (./agent_scripts/test.sh)
• Manual verification: escaped particle positions are outside domain bounds
• Manual verification: file grows across iterations (append works)
• Manual verification: surviving + escaped particles equals initial count