v0.4.0

A linting release. dotnet prolog lint reads source and reports on it without consulting it or
running a directive, so a file can be checked without being trusted. It ships with the semantic
rules on by default and an opt-in covington profile carrying the layout guidelines that are
automatically checkable, with every threshold configurable per project.

Added

• A non-executing dotnet prolog lint command with stable DPL3xxx diagnostics for singleton
  variables and repeated underscore-prefixed singleton markers. It accepts multiple files and the
  shared language modes; warnings remain advisory unless --warnings-as-errors is selected.
• A reusable PrologLinter API in DotProlog.Compiler, package-consumer coverage for the installed
  tool, and source-linting documentation.
• An opt-in covington lint profile for spaces, indentation, line and clause length, comma spacing,
  clause and subgoal layout, and trailing whitespace. Numeric layout limits are configurable while
  the default profile remains semantic-only.

Changed

• The codebase uses implicit types and the current language forms — pattern matching, switch
  expressions, collection expressions, and range and index operators. .editorconfig now states
  those preferences, so the style is expressed where tooling can apply it rather than by convention
  alone. No observable behaviour changes, and the engine benchmarks are unmoved.