bug(state): file: paths escaping the config dir (e.g. ../shared/tool) get cosmetically rewritten on save

[fentas]

Summary

LoadConfigFromPath (pkg/state/config.go) resolves relative file: values by joining them against the config dir:

if b.File != "" && !filepath.IsAbs(b.File) {
    b.File = filepath.Join(configDir, b.File)
}

For a value that escapes the config dir, e.g. file: ../shared/tool, the join produces a cleaned absolute-ish path that no longer round-trips back to the original literal. On save, relativizeFiles (added in #159) intentionally keeps such "outside the config dir" paths as-is (the ..-prefix / error guards), so the on-disk file: value can get cosmetically rewritten from ../shared/tool to its resolved form on a load→modify→save cycle.

Impact

Cosmetic only — the resolved path points at the same file, so resolution/behavior is unchanged. It's a churn/readability annoyance, not a correctness bug.

Possible fix

Preserve the user's original literal file: string through the round-trip when it resolves to the same target (e.g. remember the pre-resolution value, or relativize back even for .. paths when they still resolve under a known root).

Notes

• Pre-existing load-side behavior; surfaced during review of fix(state): keep relative file paths on save; clearer install errors #159, left out of scope there.
• Low priority.