Subtask: improve Fallow health baseline through complexity refactoring

[eviltester]

Summary

Refactor the codebase to improve the accepted Fallow health baseline over time.

This follows the Fallow adoption work in #262. Fallow health is now configured and running in CI using a regression baseline, but the project still has concentrated complexity hotspots that keep the health score below the top band.

Scope

• review the current Fallow health findings and identify the highest-value complexity hotspots
• prioritize large parser, orchestration, controller, and branching-heavy functions that materially affect maintainability
• refactor code to reduce cyclomatic and cognitive complexity without changing behavior
• add or preserve tests around touched hotspots so the refactoring remains safe
• regenerate and commit an improved health regression baseline after each meaningful reduction pass
• document any areas intentionally left as-is and why

Acceptance Notes

• the committed Fallow health baseline is improved from its current level
• the improvement comes from real refactoring, not suppressing useful complexity findings
• touched hotspots remain covered by the existing verification path
• pnpm run fallow:ci still passes with the updated baseline