Add J-lens three-brief experiment pipeline

[Atlas3DSS]

Summary

• Adds the J-lens shared utilities, persona fingerprinting runner, J-ReFT/J-LoRA pilot, local lens fitting wrapper, and Delta-J comparison runner.
• Adds persona prompt bank, July J-lens briefs, goal/execution logs, and orchestration/watch scripts for workstation + dev-box runs.
• Adds .gitignore coverage for local external dependency checkouts so nested clones are not accidentally vendored.

Validation

• python -m py_compile over all newly added Python scripts.
• python scripts/infra/jlens_three_brief_preflight.py in /home/orwel/dev_genius/venv.
• Secret scan over staged content for API key/token patterns.
• Active long-running GPU runs continue under tmux; generated sweep/log artifacts are intentionally not committed.

Notes

This is a draft PR while the overnight J-lens runs continue. Reports separate execution/provenance from findings; no substantive result claim is made from incomplete runs.