Run unified full pipeline from persona UI

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Connects Create/Update Persona to the unified full runtime pipeline.

• Runs run_full_persona_pipeline.py from the UI background worker
• Keeps UI responsive with streamed progress logs
• Runs runtime readiness after pipeline completion
• Loads persona when complete persona exists
• Auto-selects recommended policy only when readiness says READY
• Adds disk-space preflight so low disk does not crash mid-pipeline
• Recovers Stockfish once when the UI engine event loop dies after heavy pipeline work

Validation:

• python -m pytest tests/test_ui_unified_persona_pipeline.py passed
• python -m pytest tests/test_runtime_readiness.py passed
• python -m pytest tests/test_stockfish_service_recovery.py passed
• python -m pytest tests/test_stockfish_timeout.py passed
• python -m pytest tests/test_main_ui_elite_recommendation.py passed
• Manual UI smoke on D drive passed with Quick / 100 games:
  • complete persona created
  • Direct Ranker model trained
  • release gate returned needs_more_evidence due Quick coverage
  • runtime readiness returned NOT READY
  • UI safely fell back to Statistical selector
  • bot was playable after Stockfish auto-recover fix

Not run:

• Full 500-game end-to-end unlock was not run yet; Quick smoke was used to validate UI flow safely.