Issue 3: Enable and fix C4 (comprehensions) linting rules

[ParticularlyPythonicBS]

Enable and fix all C4 (flake8-comprehensions) rules to simplify unnecessary dict() calls, nested collection constructors, and redundant comprehensions.

Scope C408: Replace dict(...) with literal {...} syntax C414: Remove unnecessary nested list() or sorted() calls C416: Simplify unnecessary list comprehensions