Arch: Refactor run_output formatting pipeline

[miciav]

Problem

run_output and AnsibleOutputFormatter handle parsing, formatting, and UI updates in one dense pipeline.

Evidence

• arch_report/by_target/lb_app/hotspots.txt:3
• arch_report/by_target/lb_app/xenon.txt:4

Plan

1. Split line parsing, formatting, and UI emission into separate modules.
2. Introduce small pure functions for formatting transformations.
3. Keep a thin coordinator in run_output.
4. Add tests for formatting/line-handling behavior.

Validation

• uv run pytest tests/unit/lb_app/test_*output*.py
• ./scripts/arch_audit.sh lb_app