Clarify Swift source structure guidance

[backslash-f]

Summary

• require SwiftUI dynamic properties before ordinary stored properties
• require one top-level type per file and deterministic previews for meaningful views
• document focused function decomposition, logical enum grouping, and declaration layout
• clarify which declaration-layout conventions remain review-guided rather than swift-format-enforced
• prepare release 0.0.16 and update consumer installation commands

Why

These conventions make Swift and SwiftUI source easier to scan and maintain consistently across ThatFactory applications and packages. swift-format preserves the intended signature layout but does not expose a focused rule that can enforce it without broad source reflow, so that limitation is now explicit.

Validation

• python3 Scripts/validate_guidelines.py
• python3 -m unittest discover -s Tests -v (7 tests passed)
• git diff --check