Fix headless bootstrap and Hermes capture config

[samrusani]

Summary

• Seed the configured local Alice user during headless Ubuntu install after migrations and before doctor/alpha checks.
• Make explicit Hermes bridge_mode assist/auto enable sync_turn capture when the sync flag is omitted, while preserving strict default-off behavior and explicit false override.
• Update headless Ubuntu and Hermes provider docs, plus focused regression coverage.

Validation

• bash -n scripts/install-ubuntu.sh scripts/uninstall-ubuntu.sh scripts/pnpm_web_install.sh
• ./.venv/bin/pytest tests/unit/test_hermes_memory_provider.py tests/unit/test_vnext_release_polish.py -q
• ./.venv/bin/python scripts/run_hermes_memory_provider_smoke.py
• git diff --check

[greptile-apps]

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