feat: Add rule typo suggestion feature

[mrswastik-robot]

This PR enhances the unknown rule detection by suggesting the closest matching rule name when a typo is encountered in lint directives.

Fixes: #188

• Adds a find_nearest_rule function using Levenshtein distance from the strsim crate
• Modifies the unknown_rule diagnostic to suggest corrections (e.g., "SnackCase" → "SnakeCase")

Before submitting this PR, please make sure:

• You have added a few sentences describing the PR here.
• You have added yourself or the appropriate individual as the assignee.
• You have added at least one relevant code reviewer to the PR.
• Your code builds clean without any errors or warnings.
• You have added tests (when appropriate).
• You have updated the README or other documentation to account for these
  changes (when appropriate).
• You have added an entry to the relevant CHANGELOG.md (see
  "keep a changelog" for more information).
• Your commit messages follow the conventional commit style.

[claymcleod]

This is because you ran the tests without shellcheck installed—you'll need to do that and rerun this test.