add pure ignore comment for CSS Modules

[jantimon]

Add support for selectively opting out of pure CSS Module requirements via /* cssmodules-pure-ignore */ comments

• Comments only affect the immediately following rule or declaration
• Parent selectors with ignore comments still localize their children
• Properties following an ignored property are re-localized
• The implementation uses PostCSS's comment tracking capabilities for minimal performance impact

Initially I started with the @ prefix (@cssmodules-pure-ignore), but removed based on feedback from @jaggli for cleaner syntax.

fixes #78

Examples

/* cssmodules-pure-ignore */
#third-party-modal-backdrop {
  background: rgba(0, 0, 0, 0.5);
}

.component {
  /* cssmodules-pure-ignore */
  animation-name: fade-out;
  &.isActive { /* <-- still locally scoped */
     animation-name: disabled;  /*  <-- still locally scoped */
  }
}

The comment can include additional explanation text:

/* cssmodules-pure-ignore Modal styling injected into body */
#payment-modal { ... }

Test Cases

• Basic ignore functionality for selectors
• Animation property handling
• Nested selector behavior
• Comment scope boundaries
• Comments with additional explanation text
• Mixed local/global rules

Please let me know if you have more ideas for tests

[alexander-akait]

Looks good, today/tomorrow I plan to finish everything here and make a release

[alexander-akait]

What about just ignoring the error, i.e. don't fall and don't mix localized logic and error logic, otherwise it leads to confusion in syntax

[jantimon]

Ah you mean - you still would have to write :global?

I like the idea as it is simpler to implement and more explicit 👍

[alexander-akait]

Ah you mean - you still would have to write :global?

we basically just need to suppress errors on these comments, they should not have any effect on the generated code

[jantimon]

Sounds good - I changed it so now the comment:

• only affects the next rule
• doesn't modify the generated code
• only suppresses the pure mode error

@alexander-akait can you please take another look? :)

[alexander-akait]

Good job

[jantimon]

postcss-modules-local-by-default removes :global during processing

should we also remove the cssmodules-pure-ignore comment?

I guess the generated css would be more readable without those extra comments

[alexander-akait]

@jantimon Yeah, sounds good for me If it doesn't hurt performance

[alexander-akait]

@jantimon can you rebase?

[jantimon]

@alexander-akait done - the only conflict was the readme

[alexander-akait]

Let's avoid extra loops when mode is not pure - better perf